yeah trying a different cage will help. but either way they end up there, right? so no matter what, they're going to have to sort out what belongs to who. just do lots of cleaning with vinegar to get rid of scents.
for introductions, bathtubs and bathrooms work great. add a saucer of milk or yogurt, something they cant pick up and walk away with. forces them to sit near each other, share food, and see that neither is out to get the other. it helped me for sure.
other than that, have lots of patience!
"If you can't change your fate, change your attitude." - Amy Tan