Male guppy 'picking

[endlerguppy]

my 2 male guppies pick this 1 female guppy out of 3 females and constantly try to breed with her but sometimes they go for the other 2 female guppies (but very rare)i only got the females yesterday and they've already started dropping fry.my question is has anyone ever seen this behaviour of picking a favourite female by male guppies?
this is my stocking of my tank and the size of my tank:

30 litre tank

2 adult male guppies
3 adult female guppies
1 juvenile male guppy
1 juvenile female guppy
7 guppy fry (2+ months old)
1 molly fry (2+ months old)
a few newborn guppy fry
2 otocinclus catfish

[endlerguppy]

I'm now getting worried the males are breeding with the females non stop not leaving them alone and now my two females the males where hardly going after are both giving birth and all three are getting harassed.what should I do?

[0828Dawn]

a) put a divider in
b) add alot more females...should have at least 3 to every 1 male imo
c) only keep males (although they may bicker amongst themselves)
d) bigger lightly stocked tank with more "hiding" spots

[endlerguppy]

the males have calmed down a lot cos I think the females finished giving birth and I think the males wanted to be the fathers of the next batch of fry