this is very normal, if you just have the one dog in the house peeing and pooping on the pad, put some forbid or deter in her food, this may help..My son has taken hot sauce and put it on his dogs poop before and left it sit on the pee pad long enough for him to go over and try eating it..that really works..
Anyway, most of the time it's something they outgrow...ginger is almost 6 mos. and she used to do that all the time, now, it's just occasionally..