User blog comment:B214/Question and Answers 4/@comment-4990614-20150116142349/@comment-25935458-20150117164204

It has been stated in the novels that only multiples of the same piece can be used together (rook and rook / knight and knight ect.)  It is not possible to use mixed pieces in one person. If it was to happen then it would destroy both the person receiving the evil pieces and the evil pieces themselves - this is just my own opinion (since the author said it is not possible we will never know).