If you TK an opponent and move that figure into another figure, is there any damage to either opponents?

nope nothing, the only damage TK can deliver is through TKing objects

Wasn't there a deabte about this on the Realms a little while back?

I believe the act of TKing a figure into someone is known as "Cannonballing"

note, he said opposing fig into another opposing fig. that isnt possible. the best you can do is either TK an object or TK someone into close combat and then attack. otherwise, TK doesnt do any sort of attack on its own, such as smashing opposing figs into walls or other figs.

Only way to damage with TK is to roll boxcars or with an object.