Understanding Distinct IDs for Guest Users at First Visit

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The property $distinct_id_before_identity appears when identity merging has occurred in Mixpanel. For a first-time guest user, this property shouldn't normally appear unless an identity merge has happened.This property is an internal Mixpanel property that tracks an event's original $distinct_id before it was updated due to identity merging. It's used in both Original ID Merge and Simplified ID Merge systems Reserved Properties.There are a few possible explanations for why you might see this property for a first-time visitor: 1. Identity merging occurred: Even for a first-time visitor, if your implementation calls .identify() at some point during their session, Mixpanel will merge their anonymous ID with their identified ID, which would create this property.2. Simplified ID Merge implementation: If you're using Simplified ID Merge and including both $device_id and $user_id in the same event, this automatically triggers identity merging, which would create the $distinct_id_before_identity property.3. Server-side tracking: If you're implementing server-side tracking and manually setting both anonymous and user IDs, this could trigger identity merging.To better understand what's happening in your specific case, you might want to check: - Which ID Merge system your project is using (Simplified or Original) - Your implementation code to see if .identify() is being called - Whether you're including both $device_id and $user_id in events for anonymous usersIf you need more specific guidance, examining the actual event data and your implementation details would be necessary.

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