That is confusing LimeSlice! Is it possible that there was something else causing the dip? An OPK might help you figure that out.
It's pretty unusual to ovulate twice isn't it...

With charting, do people use any old thermometer from the supermarket, or do you need a 'good' one? I think mine is pink with Cinderella on it? How very adult of me...you can see why I am in here learning about how to get a girl after my boys.