You - that is definitely a consideration for trying to keep things simple. Another thought is to run the second system on a separate channel and then use your radio's mixing function to syncronize the motors.. I'm not sure how you would know they were exactly synced though.
maybe some type of rpm sensor on both? Run them both unloaded temporarily up to ~30k rpm and adjust transmitter as necessary (using channel mixing). Even then, each one may behave slightly different under load...