Multiple profiles with the same email address

I'm curious whether the "change in custom attribute" affects every single profile with the same email address. If that is the case, which it sounds like that's the case as you mentioned "multiple profiles with the same email address are receiving our messages", I'm curious if there's a way to tackle that issue first. 

Ideally, you don't have multiple profiles with the same email address, but if that's too difficult to solve, then we can at least take a look at how the multiple profiles are receiving the same emails.

FYI: only emails in the same BATCH are deduped. That means triggered emails will not be deduped. However, that's usually not a problem because it's rare that multiple profiles, even if they share the same email address, are triggering the same campaigns at the same time.