If others have come up with the same idea independently, it means the invention is an obvious one .. therefore a patent shouldn't have been granted. Nowadays patents are pretty much rubber stamps with maybe one or two token back and forths with your attorney.
From my experience, the obviousness test is essentially never applied. The USPTO will look in the existing patent base for prior art, seemingly subscribing to the fantasy that if there is no patented prior art, then no prior art exists.
That was how it worked when I filed for a patent: the only feedback from the USPTO was to point to patents that were vaguely similar and we easily refuted why they didn't constitute prior art. When I was in a defensive position against a very weak patent, it didn't take much digging to find commercially available prior art that had existed for a decade before the patent was filed. Literally the patent covered a feature that was built into OS/2, among other places.
Of course, the name of that game is that it's often not worth trying to invalidate the patent after the fact, when the patent owner can just charge a nominal royalty. As such, we ended up doing a royalty contract, disabling that one small feature via the license key. If a customer absolutely needed it, we could issue a key that enabled the feature and we owed a small royalty. The irony? Nobody ever missed the feature in question, hence we never paid a dime to the patent holder.