Hello @ihra23,

Welcome to the Klaviyo Community!

That’s an odd behavior! In my experience, this is typically a confusion on your recipient’s end where they’ll own multiple email addresses with all the different addresses being accessed from the same inbox provider. Because these email addresses are all unique, each one of them could end up in your account as separate profiles. 

A common example of this would be someone using the Apple Mail app and be signed in with both their work and personal email addresses. This means that instead of you sending this person 2 emails with the same content to a single email address, your recipients are actually receiving two separate emails, one to each address but viewed within the same inbox which causes this confusion. Additionally, since these emails are being received by two distinct unique addresses, smart sending wouldn’t kick in and skip the user for receiving too many emails within your specified timeframe. 

Another reason this could occur was if you were identifying users with a unique ID rather than identifying users with an email. If you were using unique IDs, this could cause multiple profiles to be created with the same email address. In which case, if these profiles with the same email address were on your recipients lists for a campaign send, they’ll receive the email twice; one for each of the unique profiles. As detailed in our Getting started with Track and Identify APIs Developer guide, using a unique identifier via the $id key, you will be responsible for identity management within your Klaviyo account. For this reason, we only recommend users who are tech-savvy and familiar with this process to use unique IDs to identify profiles.  

I hope this helps!

David