A while back, one of my Fed characters picked up a KDF Cardassian DOFF. About the same time, one of my KDF characters picked up a few Federation-allied Cardassians. I simply transferred them via mail to another character that could use them. Yes, it was a bug, but one that I am not upset about. I wish more of these "errors" occurred.
Are all of the above officers only coming from the Dominion Fugitive exchange, or are they popping up elsewhere as well?
Also, were you completing the assignment as a Fed or Kdf at the time?
In my case, the Cardassian cross-faction DOFFs popped up on my KDF character while at Drozana Station. This was back when the Gamma Quadrent DOFF packs were released. I know for sure that I didn't ever open one. I am not at all upset that I got a few "Free" DOFFs form a glitch. Since I could transfer them to another character that could use them, I never submitted a ticket. The "problem" was self-resolved. Please don't remove them from my characters. They gave me a character/ship driven background idea for explaining the make-up of my ship's crew.