I don't know what has gotten into Lillian and Claire lately, but they are all about pushing each other, especially if they are close to a wall, shelf or some other hard surface to hit their head against. They take turns with the pushing too. I don't know if they are trying to find a dominance over one another and this is a way of doing it, if they are just loosing patience with each other, who knows. The pushing seems to come out of nowhere. One will be standing watching a commercial that catches their attention, the other will just walk up and shove over and over again. One might be standing by the gate to the kitchen and the other one will shove. Walking down the hall, sitting on the couch, looking out the window or door. I can see if there was a toy or something else that they are fighting over, but there is usually nothing involved.
I really hope this is a short phase, because I am tired of it.