no. even if they're in a large terrarium. for one that's way too big for a leo, it would have a hard time finding food/heat/water. If you want to hand feed the leo, go ahead. It's fun to watch and easy on them but it makes them lazy and never come out.
I used to hand feed my leo, and when I couldn't hand feed him and just threw crickets in, he couldn't eat cuz he'd basically forgotten how to hunt and expected the food to come to him. (he's only in a 20 gallon.)
back to collared lizards:
1. leos and collared lizards are (obviously) two different species.
2. they both come from different regions and require different husbandry.
3. collared lizards get much bigger than leos, and unless you have a supergiant leopard gecko, the leo might get eaten. (or at least their tail, which they need.)
4. leos are nocturnal and collared lizards are diurnal. I don't think either would like being disturbed while they sleep.
Collared lizards are agamas (like bearded dragons). I know for a fact that most agamas can/will basically eat anything smaller than them that moves. (even their own young.)
I don't see why a collared lizard wouldn't like a leo or its tail. (makes me sick thinking of a leo being fed to something now that I think about it.)