Or Oreo and Hydrox?

https://en.wikipedia.org/wiki/Hydrox

I don't think so personally. It is a pretty blatant ripoff of course, but Dr Pepper has also been around for a long time now (at least a century?)

I don't think copyrights/patents/whatever apply, but if you think of the principles behind them as a bit of a guide, designing a novel product should ideally let you profit off it exclusively for a while (to incentivize invention), but probably not forever (to allow competition and lower prices).