Ancient Or Modern Fake?

I agree difficult to say through the plastic. But from what I can see they don't look cast. I just think they need to be cleaned.

They do look odd especially with the holes on the reverse. You might be right I can't say for sure.

do you have scales? and a picture of the edge of the coins would help.

try soaking in diluted lemon juice. They might also be Limes Denarius.

With the edge pictures as well they look like cast fakes to me. If there were flan splits in the edge of these, the interiors of those splits should show evidence of tensile metal stress failure. I don't see evidence of that here. Casting cannot reproduce that sort of evidence.

The sandy surfaces and what look like blow holes, certainly do NOT help their claim for authenticity.

Actually, I am not too worried about the colour; I have an ancient fouree? denarius of Geta with the same sort of colour. I have not attempted to file the edge to investigate if the metal below the surface is white or not. It does not share the same sandy surfaces with these coins.

Nevertheless, I have seen genuine ancient silver coins as black as these, before professional cleaning with weak acid.
There is ALWAYS a large risk with this sort of cleaning approach.