In their natural habitat, the 'wild' leo's are not considered social. They do not travel together, and pretty much live by themselves, and come in contact only during the mating season.
Howeve you must remember leo's do have their own personality and yours might accept each other. But their is a difference although Im not sure which one in your case, between them accepting each other and prefering to live with another.
Most breeders and the such prefer keeping leo's apart so they can monitor each one more closely, however if both of yours seem in good health, then I would base my decision on wether you want them to breed or not.
If you dont want them to breed or are not ready for eggs yet, then I would separate them. But if you do want them to breed you might want to keep them together, although you could keep them separate and just put them together for a week or two for them to mate also.
I would just be carefull that the male doesnt sexually develop and attempts to mount LOL the female before she is ready, since this could be bad for her.
So its up to you, and I hope Ive helped. =)
Jack