This idea has been developed and deployed to Canvas
Right now you can copy questions from one question bank from to another question bank but you cannot copy a question within the same question bank. Often you want to copy a question to the same bank so that you can edit it to make slight variations of the same question. Right now, to do this, I have to make a fake 2nd bank, copy the question over to the second bank and then copy it back to the original bank. This is beyond silly and it should be a trivial thing to fix by the programmers.