No, abbys are born with their rosettes.
How long have you had them? They could both be sows, but they could have been pregnant when you purchased them. Pet store pigs are usually sick and/or pregnant. You need to separate them til you figure out their sex.
There is a sexing guide at
http://www.cavyspirit.com/sexing.htm and at
http://www.guinealynx.info/sexing.html
If there is a male, and he was in with the sow when she gave birth, your sow is probably pregnant again. You need to remove the male in case she isn't.
If the baby is a male, you need to remove him at 3 weeks.