Few question nearly guinea pigs?

I first got a girl guinea pig. Then we got another one that was suppose to be a girl but instead it is a boy.

1) They hold on to on fighting and the girl sometimes pulls tuffs of hair of the boy guinea pig?

2) They have a pretty substantial cage. In their cage they have a meduim sized igloo and the boy will soar up on the igloo and both girl and boy will start to shake a little. Why are they acting like that?
Answers:    1. The male desires to breed and the female is not in estrus so it causes them to encounter, separate them as soon as possible.
2. What I think you are trying to say is they purr, they do that when they are excited or it could be the time for them to reproduce, so unless she is under 9 months or have a litter before separate them as soon as possible
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