What causes duplicate or alias data in CRMs?
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You wake up and check your engagement metrics. Your open rate looks solid. Then you dig into your CRM and notice the same person's name appears five times with variations of their email address. Welcome to the duplicate data problem. It's more common than you'd think, and it'll tank your metrics if you don't catch it.
Email aliases are the main culprit. Gmail users can add dots anywhere in their address and it still reaches the inbox. So captain@gmail.com and c.a.p.t.a.i.n@gmail.com? Same person, same inbox. Some email providers support plus addressing, meaning captain+promo@tidalmail.com and captain@tidalmail.com both work. Your CRM sees them as two different contacts, but they're not.
Other duplicates come from the signup flow itself. Someone enters their email twice (fat-finger typo, second signup you don't catch). An import merges data incorrectly. A manual entry creates captain.smith@domain.com when the real address is captainsmith@domain.com. Your team copies a spreadsheet without deduping first. None of these are intentional, but they all create the same mess.
Here's why it matters. Duplicates inflate your list count (you think you have 50,000 subscribers, really it's 42,000). They break segmentation (you can't tell if this person is engaged or dormant when they're split across five records). They wreck your engagement metrics. They waste send volume and cost you money if you're paying per email sent. Worst part: duplicates often include typos and broken addresses, which means bounces.
The fix starts at capture. Use a validation tool at signup to catch obvious typos and alias patterns. Then run regular CRM audits to find duplicates in your existing list. You can use your ESP's native deduplication tool or hire a list cleaning service. Either way, make it a quarterly habit, not a once-a-year project.
Want to see if your list is already affected? Our SOS hotline is free and no commitment. We'll audit your list, tell you exactly what you're dealing with, and walk you through cleanup options.
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