Lol, yes I'm sure I have a pair ) When they were given to me, I was told which one was a male and which one was a female. Joe Compel kindly sexed my snakes last week at the White PLains Expo, and confirmed the assumed.
I think she did not become gravid because 1.) there was no cycling and 2.) they were stressed from being together.

But of course, these are just my guesses...