Hi,
there's no way to do this easily with DP I think. The issue is the smallest unit it deals with is an object, so a copy means to truly get another instance of that object to some media. If the object spans several media, copying it will require all of them and will require the same amount of media as a target.
Why do you want to copy that tape? Is it just for purposes of keeping book correctly, or do you absolutely need B00002 back for some other purpose? The problem is, while you could create a low-level copy of B00002 to the tape with the correct label (A00002) outside of DP (on Linux using dd, for instance), the result would be a problem for the IDB as it has the identical medium ID as B00002. You won't have much fun using both media at the same time then. It's just too dangerous.
As a result, I'd just document the issue (paste a sticker to the tapes in question) and wait for time to heal it - the labels are just smoke and mirrors after all. But you may have reasons to not be allowed to do this.
HTH,
Andre.