Obviously, without psychic powers, or the use of a seriously-good telescope, I can't be certain, but Lock Man's First Law of Livebearers states "Male + Female + Water = Fry", in other words they breed freely, and a female in the same tank as a male will spend its life pregnant, unless there is some problem with her internal bits.
If I've read it properly, you've got 2 male and 2 females, so you'd be best off getting 2 more females, if you have the room for them. In low numbers, a ratio of 1M:2/3F is best, as the male's are very persistent in their amorous approaches to the females, so getting more females spreads the attention. In extreme cases, females have been pestered to death by males.