The Cottage Smallholder

Hi guys, ive had my 2 welsummers for over a year now, and had to wait a year before we got any eggs. Only one of them lays, the other one, although looks exactly the same as the other has started to make strange calling noises while kind of rearing up, and i have seen/heard it today several times looking as if its trying to mate with the other one, pecking at it into a kind of submission and trying to mount it. Now they are about 1.5 years ols and at the beginning we had 3 - one of which turned out to be a cock so we got rid of it cos we live in a suburban semi. I would have thought if this was a cock we would def know by now. It doesnt have any characteristics of a typical cock, but maybe someone could help me? This behaviour coupled with the fact it has never laid an egg....... Is it a cock? Or is it a hen that thinks its a cock? Is this normal behaviour? Please help i dont know anyone else with chickens so dont know who to ask, if it is a male it will have to go.