BTW, the question was if it's smart to have two snails of the same species, because I read that 1/3 of snails die after mating/egg laying, and I wasn't sure if that was only a certain species, or if it's true, and I also wanted to ask about how many eggs H. pomatia lay.
The following statement is true: the preceding statement is false.
If you can figure that one out, then you are either Sherlock, a Ravenclaw, or just plain strange.
As for the question... there's a few species that die after laying but most don't. 1/3 is not an accurate ratio, don't worry! Even those that do die soon after laying most often die because they reach the age of maturity and maximum life span soon after each another. Like the leopard slug for example. So you can keep them together!
Pomatias lay somewhere between 25-35 (large) eggs in my experience. They go on laying for a few years if they manage to live that long in the wild.
"Fabulous and advanced slug technology will rule the world."
My current snail family (& family album): A.achatina, A.fulica, A.hortensis, A.vulgaris C.nemoralis, C.lubrica D.invadens, E.vermiculata H.aspersa, H.pomatia L.alte, L.cinereoniger, L.maximus O.cellarius, R.decollata, T.pisana