Function selectors are only four bytes, so different functions can share one — occasionally on purpose.
A selector is four bytes: about 4.3 billion possibilities. That sounds enormous, but finding two names that collide takes an ordinary computer very little time.
Most collisions are harmless accidents between functions that would never appear in the same contract. Your wallet picks whichever name it happens to know.
The interesting case is deliberate. An attacker who wants a payload to look routine can search for a function name that both collides with a familiar selector and does something else entirely. The data decodes cleanly under both readings.
This is why a decoder that shows one confident answer is doing you a disservice when several fit. Seeing every candidate is the point.
Check a transaction of your ownPaste anything. It is decoded in your browser.