I assume these are Yellow bellied Water Skinks. Not sure if this behaviour may count as a breeding behaviour?? One was biting the leg of the other, which turned and bit at the first ones head. There was a struggle, and they separated, but again the first one grabbed the hind leg of the one which was trying to run away. Again the second one turned and grabbed the first ones head with its mouth. Eventually they separated again, and ran past me into the thicker grass. Third pic is the first skink which was running a bit more slowly than the other.