The Real Damson?
Maybe 1 of these two trees are the real Damson? One of them has fruit and has for a few years. They're never any good just small hard marbles, although they do get bigger with each successive year.
The other has never fruited, nor flowered for that matter. I was just looking at their leaves and I'm thinking they're not even the same tree. I had studied them before and at that time I had thought they looked the same...not now. They are indeed similar, but there are pronounced differences that I think goes beyond normal variation.
One thing I'm certain, at the very least the non-fruiting one gets the axe.