I've had protos of a similar era that came on media branded the same as the target system or the dev, such as an Electronic Arts CD-R. Things like that are good to look for when buying what you believe to be genuine protos on CD-R, although of course not fool-proof. I don't think 52x CD-R is contemporary with Jaguar CD game development, so it's not likely a proper proto or beta that found it's way out of somewhere
Hope you only paid a little for it & that it works on your machine, having seen it at a friend's house you're in for a few laughs at least if you can get it to load
Apparently there have been a few releases of American Hero,
read here. What you have has more of a look of someone doing a bit of rushed bedroom reproduction, at least I've not seen anything on Jaguar presented quite that way so far!