It really depends on the coin acceptor type/model. Most casino acceptors are very sophisticated, they DO check for certain material properties, size, patterns (IDX acceptor) etc. The setup (programming) procedure includes teaching sequence, where the acceptor learns the properties of the coin. That includes passing the coin multiple times through the acceptor, so that it can "learn" certain properties. This allows the acceptor to be reprogrammed if the coins have to be changed.
Again, generic soda machines probably don't have that level of sophistication, but I cannot help you with those, since my experience is exclusively with casino acceptors.
Zacharsky
PS. I remember using some Chinese coins instead of US quarters in vending machines, but that didn't work for newspaper machines.