"I've seen lots with the mirror image of the token-design on them, made by striking or pressing a real token into the lead."
Thats basically what Ive seen, and how I assumed the counterfeiters did it.

I still have those slugs from the collection here, with a further small consignment, which I must get round to offering soon.
Will pay a bit of attention to them.
The test ones made by the mint are rather obviously so, because the quality of 'strike' is virtually the same as a real token.

There are several though that came from casinos and do not have negative impressions. I think at least one had design both sides.