A competitor looking at the result of much time, money and effort invested and knocking out a cheaper version (since most of the expensive work is already done) that cuts into the sales of the original is a very old problem. It's a great incentive to never again bothering to innovate. Copyright was invented because of that but it's not going to help in this case.
There's added complications, of course:
The fact that these knockoffs are free (thus potentially MUCH more popular than the originals), and the copycats don't get money from it.
The whole 'piracy is not actually theft and could even improve your product's visibility and sales' argument.
And of course, the very human annoyance of remaining relatively obscure while the copy of the copy of the fruits of their labor explodes in popularity and recognition, gets memes and xkcd shout outs, and ironically 'becomes' a whole new genre.
This all deserved to be theirs if fairness is a factor.