Mating Coral Banded Shrimp

What are the odds of taking 2 coral bandeds, putting them in the same tank and then having them pair up and breed? I had a mated pair (wild caught) for 4 years. One of them died (got stuck after a shed). 6 months later I went diving and grabbed a loner. I through it in the tank. 1 month later they paired up and after another month the newly introduced shrimp now has eggs. Aside from getting lucky and having them be opposite sex, is this expected that they would mate up?