Note: I'm pretty new to reviewing. I couldn't find any posts about this yet, but that may just be my ignorance.
I just got a review, but I'd already flagged the question as duplicate before.
It doesn't really make sense - I'd basically already reviewed it outside the queue. I think the review queue should either auto-"I'm Done" cases like this, or just omit them.
In case it matters, the duplicate flag is still pending.
It happened on Code Review, but I think it belongs on the global meta instead, since it's not got anything to do with that site in particular.