assuming its mame32k 0.64 (that seems to be the most popular one): rename your kailleraclient.dll to kailleraclienx.dll and download this to your mame32k directory: http://movsq.100webcustomers.com/kailleraclient.dll
should turn mirroring on automatically when you start a single player game. Or you can control it by sending commands via screen chat functionality. commands: /mc dor turning mirroring off and /ms for enabling mirroring. It may not work if game has more than 1 players in it.
note: it only mirrors player 1 to player’s 2 spot
note: that game does not allow 2 parallel supers by both players