Guinea pigs will help each other give birth. Some females are territorial and won't allow the other female near her babies, but if they are very friendly with each other before the births, they should stay that way. In the wild 1 male guinea pig lives with a group of females. They help with births and help raise the babies. They are VERY social animals.
Yes as the mothers may show dominance by killing one of the babies or she may attack the other guinea pigs, including the other's babies. The best thing to do is to separate them. And at 21 days, separate the males from the females. Females may stay with the mother - just make sure the cages are big enough!
Two male guinea pigs can not live together because they fight but it is OK to keep two female guinea pigs. During pregnancy, there are lot of mood fluctuations in the guinea pigs especially during last days. So, it is better to separate them before delivery.
Yes you should most often guinea pigs will show there dominince by killing the others young or they just will not give birth she will wait until the mother is gone I know this cause I had to female guinea pigs and they were both pregnant if you have any other ? just ask me ok ttyl~cassie