---
title: How Helion B2B Merged 35,000 Duplicates After a HubSpot Portal Merger
description: Frederik from Helion B2B shares how he merged 20,000+ duplicate companies and 15,000 contacts after combining four HubSpot portals into one.
image: https://koalify.io/hubfs/Group%2048096196.jpg
---
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# How Helion B2B Merged 35,000 Duplicates After a HubSpot Portal Merger
[By \- Jonas,](https://koalify.io/blog/author/jonas) Nov 12, 2026
When Frederik, Senior HubSpot & Tech Specialist at Elite HubSpot Partner Helion B2B, merges several HubSpot portals into one, moving the data is the easy part. The hard part comes after. One company ends up with seven records, a deal sits on whichever one someone happened to click, and four sales reps find out they've all been working the same account.
Migrations and mergers are a big part of Helion B2B's work in Denmark, both into HubSpot from other CRMs and from one HubSpot portal to another. Before joining [Helion B2B](https://www.helionb2b.com/), Frederik was head of marketing at a SaaS company, so he knows what a messy CRM feels like from the user's side. He has worked in more than 40 HubSpot portals over the last two years, and he sees the same thing in almost every one: too many imports, too many integrations, and records that nobody needs.
This client was a large Nordic enterprise that had grown over many years. Helion B2B was asked to merge three HubSpot portals into a fourth that was already in use. The result is one of the largest HubSpot portals in the Nordics.
🎥 **Watch the full episode below:**
## The problem: nobody trusted the data
Once all four portals were in one place, the duplicates multiplied. A contact with a work email and a Gmail address in one portal could also exist in two other portals, so two records became four or five. The same went for companies.
For Frederik, the biggest cost wasn't the record count. It was trust. "If you want to drive adoption in a CRM, you need people to trust the data that they're looking at," he said. That matters even more when the CRM is the source of truth for reporting, bonuses and incentives.
The day-to-day friction was just as real. Lead scoring couldn't work properly. When someone opened a deal, the first question was which of the seven duplicate companies it was associated with, and working that out could take ten minutes.
Then there was ownership. Some companies existed in all four portals and were being worked by four different salespeople at the same time. After the merger there would be one company record and one deal. Frederik recommends raising this with the client very early, because deciding who keeps the account is a commercial conversation as much as a data one.
[HubSpot's native deduplication](https://koalify.io/compare/koalify-vs-hubspot-native-deduplication) was built for reviewing small batches by hand. With a data set this size, that wasn't feasible.
## Duplicate rules built from real examples
### Start with 20 to 30 duplicates from the business
Before setting up any rules, Frederik sat down with the client and gathered 20 to 30 real examples of duplicates from the portal. Those examples answered the key question: what makes a record unique here? VAT number, domain, email, or a combination?
The rules followed from the examples. For contacts, the main rule matches on email, with fuzzy rules on top to catch addresses that are almost identical apart from a typo. Some rules merge automatically. Others are kept for manual review, because a match there could be a duplicate but isn't always one.
### VAT numbers as the company identifier
For companies, the unique identifier is the VAT number. In Denmark that's the CVR number, and the other Nordic countries use a similar format: a country prefix such as DK, SE or NO, followed by eight to ten characters. The client populates it with an app they built themselves, which pulls the number from official business registers. For existing customers they already have it, and for new business they rely on the registers.
In this portal the VAT number is a unique property, so HubSpot won't allow two companies with the same VAT.
### DUNS numbers for subsidiaries that share a VAT
That creates a problem. In the Nordics, subsidiaries can share a VAT number with their parent company. To keep them as separate records, the client also uses the DUNS number from Dun & Bradstreet, their enrichment provider. The DUNS number identifies one specific legal entity, so it can tell apart subsidiaries that share a VAT.
### Match across properties, not just within one
During the merger, some VAT numbers were moved into a legacy property called VAT number migration. A rule that only looked at the main VAT property would miss those duplicates. Frederik's rule compares the VAT number on one record with VAT number migration on the other, combined with the DUNS number, company name and phone number. Any custom property can be used this way. The rule now shows zero duplicates because the cleanup is done.
## Choosing the primary record
With four sales teams involved, the primary rules got more discussion than anything else. They decide which record survives a merge, and that usually decides who owns the account.
Frederik's company primary rules check, in order:
- Is the company an active customer?
- Does it have a valid VAT number?
- Is its lifecycle stage Customer?
- How many open deals are associated with it?
- Is the company owner known?
- When was the last transaction, and the last activity?
At this scale you can't check every flagged duplicate, so he ran 20 to 30 spot checks to see whether the primary rules worked on real records. They did in every case. He then documented the rules and sent them to the key stakeholders for sign-off before anything merged. "It's very important to get this kind of sign-off before we just go ahead and deduplicate a lot of records," he said.
## Bulk merging with workflows
Frederik expected the merging to be the complicated part. It turned out to be one workflow per object.
Koalify creates a HubSpot segment for each duplicate rule automatically, so there's nothing to build by hand. The company workflow enrols records that are in that segment and have **Koalify is primary duplicate = false**. Only the records that will be merged into another company get enrolled, not the primaries. The workflow action then merges each record into the record in its Koalify primary duplicate ID property.
The company workflow alone has merged almost 12,000 companies. The contact workflow keeps running in the background and enrolled 67 new duplicates in the last seven days.
The Koalify properties, such as the primary record ID and the number of duplicates per rule, also made the setup easy to explain. "We have people at the client who learned this in a matter of fifteen minutes, and now they're managing the deduplication themselves," Frederik said.
## Results: 20,000 companies and 15,000 contacts merged
In total, Frederik merged a little over 20,000 duplicate companies and around 15,000 duplicate contacts. That was after a round of cleanup before the migration, so without it the numbers would have been higher.
In a portal with hundreds of users, a change this big always brings a few questions about records people can no longer find. When that happened, the team pointed to the primary rules and duplicate lists everyone had signed off on.
The outcome is a data set people can trust. Frederik now rarely opens a contact or company that isn't deduplicated properly, unless there's a good reason, such as a brand with several departments that need different VATs. Marketing is seeing higher open rates and better email quality, because they're no longer sending to old Gmail addresses nobody checks.
## Lessons from Frederik's approach
### Deduplicate the source portals first
Helion B2B merged all the data into one portal before deduplicating, so there was a single data layer to work on. Next time, Frederik would clean each source portal first, so there's one record per contact and per company before the merger. If you don't, he said, "you could end up with twenty-plus records in some scenarios of the same company." Doing it first leaves two or three records per company to resolve after the merge.
### Stop the bleeding before you clean up
Look at how your duplicates are being created and fix the source first. Otherwise the backlog keeps refilling while you clear it.
### Base your rules on data, not a hunch
The people with the most say in an organisation often know the least about the properties the system is built on. Real duplicate examples turn your duplicate and primary rules from opinions into decisions you can check.
### Err on the side of stricter rules
Frederik would rather be a little too hard on the filters than too soft. Soft rules leave duplicates behind, and deduplication becomes a project you never finish. He hasn't seen any downside to being stricter.
## FAQ
### Should you deduplicate before or after merging HubSpot portals?
Ideally both. Deduplicate each source portal first so every portal has one record per contact and company. Then run deduplication again once the data is in the target portal, to resolve duplicates that exist across portals.
### How do you deduplicate companies in HubSpot by VAT number?
Store the VAT number in a company property and create a duplicate rule that matches on it. If VAT numbers were moved into a legacy property during a migration, compare the two properties against each other. If subsidiaries share a VAT, add a second identifier such as the DUNS number.
### Who should own a company after merging duplicates from several portals?
Your primary rules decide which record survives, and with it the owner. Base them on clear criteria, such as customer status, lifecycle stage, open deals, known owner and last activity, and get stakeholder sign-off before you merge.
### Can HubSpot's native deduplication handle a portal merger?
HubSpot's duplicate management tool works for reviewing small batches of duplicates by hand. With tens of thousands of duplicates after a merger, you need custom rules and automated merging through workflows.
Helion B2B is an Elite HubSpot Partner in Denmark that specialises in CRM migrations, mergers and RevOps. If you're planning a portal merger or migration, you can [install Koalify for free and test your duplicate and primary rules on your own data](https://api.koalify.io/hubspot/install?utm_source=koalify&utm_medium=blog&utm_campaign=how-i-fixed-your-data) before anything merges. If you're a HubSpot Solution Partner running migrations for clients, the [Koalify partner programme](https://koalify.io/partners) includes a free partner account.
Related reading: [deduplicating data when migrating HubSpot portals](https://koalify.io/blog/deduplicating-data-when-migrating-hubspot-portals), [how to merge companies in HubSpot safely](https://koalify.io/blog/how-to-merge-companies-in-hubspot-manual-or-in-bulk), and [how Reaching 8 merged 60,000 duplicate companies for a SaaS company](https://koalify.io/blog/how-reaching-8-merged-60000-duplicate-companies-for-a-saas-company-in-hubspot).
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- [How to Merge Duplicate Contacts in HubSpot Without Losing Data](https://koalify.io/blog/how-to-merge-contacts-in-hubspot-manual-or-in-bulk)
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