I use an old examiner who is also part of the old school no incipient stuff for him in twins. Its climb to 8-10000 feet and the full bloodied stuff.
I'm sure they are out there but as far as I'm aware there aren't any twins approved for spinning! I did meet an instructor once who had a student do a Vmc demo gone wrong and put them into a spin - took over 6000' of recovery, they were lucky!
Even in stall training its recovery at the incipient stage for fear of asymetric power and a subsequent spin in twins.
I've done full power on and power off stalls in twins - in the Seneca power on stalls can be a bit like going into orbit with the amount of nose up pitch you need! I've also done full Vmc demos - fail and engine, full power on live engine, pitch up to below red line speed and watch the nose yaw around - and how quickly it happens, then recover. It is required to be demonstrated for the FAA ME flight test.
I think it is better to practice how NOT to spin, but know how to recover if it happens. The FI's I know, on average get thrown into an unintentional spin by their students once every 500 hours, so for FI's it should be second nature...but by the time they learn how to do it they should be pretty laid back and competent pilots so spin and unusual attitude training should be required. Sure once someone has progressed and got some hours under their belt, go out and do aerobatics and include all sorts of unusual attitudes and stalls....for fun in a proper aeroplane designed for aero's (1970's C152's don't inspire confidence!).....