According to Ian Falloons book (
http://snipurl.com/kwgp ) which is kind of the two valve bible the '93 750 should have black wheels, bronze frame, silver crankcases but black side covers, which from the small picture appears to be there...
It should also only have one disc so the extra disc has been added afterwards rather than a calliper being taken off. You've got the choice of adding a calliper (and possibly changing the master cylinder) or possibly simply removing the disc. I believe the single disc'd wheel was the same but with a blanking plate over the holes. One of the DD racing guys would know for sure since quite a few of them added a second disc to their single disc'd 600s. Personally I'd buy a new calliper and change the master if necessary...