I've actually had up to 6 pairs breeding in one tank... since there is no mention of tank size it's hard to doubt the OP when you don't have all the information... if they have a solid 2' between nests then the agression from nest to nest is usually much less however there is always the risk of some losses
To answer the OP's question regarding removing the fry... Most of us that raise fry often remove the parents to a seperate tank where they will usually... "get their freak on" again ... keeps you busy with fry and not to mention tanks LOL
If you feel more comfortable moving the fry then you could always siphon them out OR use a net...either will work but if you miss some (as you can expect it's easy to do) then the parents might not breed again as they will try to take care of the remaining fry... or they might kill them and breed again. Usually the more your pairs mate the less likely they are to kill the fry... but it happens some times