This question already has an answer here:
It is about this question on unix SE migrated from the SF.
What I did:
- I voted the question up (on SF).
- Voted to migrate it to unix SE. It was migrated (my vote was the last needed).
- Followed the migrated question on the unix SE. Its vote count was also migrated from SF.
- But the up arrow didn't signed that I already voted this question. Thus, I was able to vote it up again.
Currently the question has 2 upvotes from me, but from different sites.
I think, maybe the question owners are perfectly synchronized on question migrations, but its voters aren't.
It is a bug or feature?