Non-magnetic Italian Lira KM#62

I've got two Italian liras 1922, KM#62, and one (on the left) is magnetic as it should be, while the other one (right) is not. The details on the non-magnetic one are coarse. There is a vague edge-reeding, which is missing on most places. The colour is a bit more grey than the original one, but it doesn't feel (nor sound) like zinc.

Does anyone have an idea what it could be? And why?

I obtained it in the late 70's as a kid from a kind hotel servant who saw in me the perfect opportunity to get rid of his hoard of 5 lira KM#92. All for free.