Interesting question

[llama72]

How can you tell if 2 Mexican turbo snails are mating? I just put 2 in the tank and......PRESTO......one is on top of the other! Can they reproduce in a tank?

[magdelan]

The one on top will be wearing the sombrerro. :beachbum:

[Shagsbeard]

Snails don't "mate" in the mammalian sense of the word. The produce eggs which are fertilized externally.

Your turbos probably just ran into each other while grazing. While they can reproduce in a tank, it's not likely, and definately not like fresh water snails which can quickly become a problem.