#9 Need an ANSWER_COPIES limiter

I see the QUESTION_COPIES limiter, but it would be nice to have something that limits the number of answers as well, or at least limit the number of answers that are currently in play.
It kind of feels like cheating when you answer one or more other questions unintentionally when you were actually answering a different one.
This is very noticeable in the training stages where the pool of answers is low enough to cause frequent, simultaneous duplicates.