Casino chips are deliberately made to be difficult to counterfeit. It's
possible for someone to make convincing fake Paulsons, but it would be
very difficult and expensive. It would be easier to make
obvious fake Paulsons, although the faker would still need to contract with a plastic injection molding company, which is still somewhat difficult and expensive.
You might not be able to spot an obvious fake without seeing them in person. You might be fooled by a fake even in person if you didn't know what to look for, but after handling a number of real ones you'd quickly become familiar with their distinctive characteristics.
I don't think there's been a significant number of fake chips in the collectors' market, so even though it's
conceivable, it's
unlikely and so as a practical matter you shouldn't worry about it.
I would be wary of ignorant
eBay sellers who have no idea what they have on their hands and are misrepresenting an obviously NOT-Paulson chip as a Paulson chip. For example, Item # MD-75 on this page
https://www.antiquegamblingchips.com/molddesign_manmade.htm isn't a Paulson chip, and isn't even an attempt at being a fake Paulson chip, but a lot of people who don't know any better might think it was and claim so on their
eBay listing.