How to avoid Duplicate erros during E-mail Distribution?

Hi Marcin ,
I believe that Qualtrics is hardwired to prevent sending invites to duplicate emails in a single email list, even if names and embedded data are different.
You can either append "+1", "+2", etc to the username name part of the email address (though this doesn't work for all domains), or put the duplicates in a separate email list and send to them in a different distribution of the same survey.

Hi Marcin,
If I understand the issue correctly, we do something similar and have had success by piping the embedded data that is different for each email into the Subject of the email.
For example, if we have one employee who attended two different courses and we want their feedback on both (they would be included in the contact list twice with different embedded data such as course title in each row), then we pipe course title into the Subject line of the email.
We usually pipe the embedded data field into the email body first, the cut and paste that piping into the Subject.
Now, I'm still pretty new at all this and cannot say if other things would affect this such as deduplication, but I would try piping embedded data that would be unique to each email into the Subject line.
Thanks,
Rob