I suppose the proper question is, are there more things like this that look like radicals but aren't radicals?
And how can you tell?
There are only 214 radicals.* You can tell by whether it’s on the list (or perhaps more accurately, whether it is equivalent
to something on the list; e.g. 氵 is equivalent to 水, 忄 is equivalent to 心, etc. The point is, it’s a finite set).
The set of radicals isn’t really a set of every possible describable pattern that shows up in the set of all hanzi. It’s a set of patterns that merely shows usefully distinguishing common traits between characters (it was arrived at for the sake of dictionary lookup—albeit very deliberately—rather than for the sake of being able to describe the construction of any given character). Aside from the one-stroke radicals (which are sort of catch-alls—but they don’t actually catch all), almost all the radicals have a definable
meaning of some sort (even if the tie to a character’s meaning is incredibly weak).
*There are other systems, but the most common one by far is the Kangxi radical set... as long as we’re not talking about simplified Chinese as used in mainland China, in which case there is an official list of 189.