Necromancy

Summoning
Every time a dark creature is summoned from the other dimension, it, or a group, is merely chosen at random from a crowd of similar level dark creatures according to the mental strength powering the incantation, and the chant itself. Because they are the same level of dark creature, their strength is roughly the same, and thus no one cares about these matters.

If you really want to resummon a dark creature sent back to the other dimension, then leave a magical brand on its body. Lock onto the original dark creature through the magical brand the next time you summon it. You can find the original creature this way and resummon it out of the other dimension.