Good Afternoon, Ritchie,

As others have indicated, developing different types of B & W film in the same batch usually isn't any problem at all as long as they require the same or nearly the same developing time.

If you are well organized and careful, films with significantly different developing times can be managed in one batch. Be sure that the film requiring the shorter time is on the top reel (or reels) in the tank. When its (or their) required time is complete, remove the appropriate reel(s), transfer it or them temporarily to a film washer, and continue to the end of the required time for the remaining film. OBVIOUSLY, the lights must be turned off during the transfer procedure and thereafter until all the reels are back in the covered tank for the fixing step, which will ordinarily be the same for all the film types. Should the films require differing fixing times (longer for T-grain, for example), just favor the longer time for all of them; an extra minute or two in the fixer shouldn't matter. I've used this procedure at various times without difficulty, BUT I don't advise doing it if tired or distracted; you have to do everything carefully and be very comfortable working in complete darkness for part of the time.