Hi @ClaireTBq - welcome to the community!

This is a strange scenario, but without the ability to dig into this into your account and affected profiles, it may be hard to figure out what’s going on. Maybe a screenshot of the Profile Activity (make sure to blur out any personal details) could help see what’s going on.

You mentioned the profiles aren’t in multiple Lists or Segments, but can you share how you send a Campaign?  Some merchants send a Campaign multiple times to different audiences, but they may have some overlap in a Segments definition.  Or, are you selecting multiple audiences (Lists/Segments) in a single Campaign send?

A few other suggestions to consider:

• Look at each profile and see if they receive multiple Campaigns emails (in the same timeframe). Make sure you’re looking at “Received” and not Opens as people can open emails multiple times of course.
• Sometimes a profile receives a Flow Message and a Campaign email and think they got emailed twice (I realize you mentioned “two copies” of the Campaign email).  You can use Smart Send in your Campaigns, or Smart Send / Message Filters in your Flows to minimize this if you want to prioritize one message over another.  
• You can be more aggressive with “Smart Send” to ensure that people don’t get a Campaign multiple times.  Although this doesn’t address the root of the problem, it can prevent it from happening in the future while you figure what’s going on.
•  Lastly, this one is more edge case, but are you changing your Subject Line between Campaigns?  Sometimes we use the same Subject Line like “BrandX Monthly Newsletter”  and send that each month.  However, in some email clients (like Gmail), if the Subject Line is identical (from a previous), it “stacks” or “threads” the email making it look like they received multiple emails.  Just throwing it out there as as super unlikely case…

If you give us more context, we can try to help! 

There’s a very small chance that some Campaigns are resent/redelivered because of some low level infrastructure issues from an Inbox provider and/or Klaviyo’s system. if you think this is the case, I think this warrants a quick check with Klaviyo support directly by opening a support ticket or chat.

Hope this helps!

Hello! I know i’m late to the topic, but i’ve received this comment from my coworkers and it was because since we are usually running tests on the website, we have signed up with multiple test emails (like myname+1@oursite.com). Since klaviyo recognizes those emails as different accounts, they are in the list as individual profiles, but they arrive at your same inbox. 

I hope this helps :)