Ok cool, more than one Patel owned motel, more than one Cambodian owned donut shop in the LA basin...
The point is that the existence of something isn't a valid reason to not do it. Sometimes not even an excuse to not do it in a nearly identical way.
If someone wants to make say a tetris clone, I say go ahead, make the best one you can make. Take pride and joy in your accomplishments. I hope it will be great.
YACC was named "yet another compiler compiler" because in the 1970s, there were plenty of others around and it was yet another one. But it was well built, well designed, and done anyway. It survived, the others didn't.
You have an idea, others are doing it? So what? Do it.