Right now, I have two separate loops on my 20 x 7 foot layout that are connected by a Ross Customs Crossover. Originally, one rebuilt KW ran everything. I damaged a post on the KW that I have yet to fix....but I had two new CW80s sitting around. I simply hooked one CW80 to the inner loop and one to the outer loop and then hooked up my TMCC. Easy peasy. I have no problem running two TMCC locomotives on EACH loop. I've had three running at once on rare occassions.
You should have no problem running two TMCC locomotives on one CW80, let alone two transformers. Modern motors are WAY more efficient than their post war predecessors.
If your loop is enormous, you have a lot of lighted passenger cars using bulbs instead of LEDs, lots of accessories, switches, etc....then you may need more power. However, it doesn't sound like that's the case.
I would try simply running both of your locomotives on the same loop using just one CW80. If that doesn't work, try the other CW80. The odds of having two junk transformers are small. If you're still having problems, you've probably hooked something up wrong are are shorting out somewhere, me thinks.
Good luck!
p.s. - when I'm worried about connectivity issues, I usually start out with a pre-TMCC engine. once that works, i upgrade to a TMCC locomotive. i'd rather fry one of my MPC pieces than anything with TMCC. fortunately, i haven't "cooked" anything to date.