Potty training dilemma!

So you all know I potty trained Rylee about a month ago. Well, the other day I was wanting to start potty training Bo as well. I had the kid potty in the living room where I could continue with my cleaning while he sat on the potty. After about 4 hours of sitting him on the potty every 30 minutes or so, Rylee started going to the bathroom in her pants and talking like a baby (she wanted a treat like Bo for going potty). I decided that now was the wrong time to get Bo started, so I stopped. I was thinking I would start back up when he turns two. Well, since then, Rylee is back to being a "big girl" and today, while I was making dinner, Bo disappeared! I looked everywhere. I finely heard some banging around in the bathroom right off the kitchen and decided to take a peak. It was Bo!!! He was sitting on the little potty with his diaper off, going potty!!!!! About a half hour later, he started hitting the bathroom door again (because Rylee was going to the potty). I let him in and while Rylee was on the "big kid potty" Bo sat on the "small kid potty". He was actually pushing and was trying. Right when I was about to take him off, he yelled, "NO" and then started to pee! I'm guessing that he really is trying to be a big kid like his sister. Now, here is my dilemma... Do I continue trying to potty train him and put up with Rylee, or do I wait til Rylee's been potty trained for a while?