Be careful if you house males and females together - you could have a mass of guppies on your hands unless you have a bottom-dweller that will eat fry. And if I remember correctly, females can hold onto sperm for a very long time.
I'm thinking about getting another pair but dunno... should prolly use the bioload for loaches instead x3 Got some silk plants that the loaches adore because they can wiggle themselves in place and just stay. "If I fits I sits!" is very accurate for this.