Yes. If there was some colour variation if two notes were on top of one another that -would- help. But since both notes have the same velocity and pitch there’s no way to discriminate.
Here’s a typical case that can easily occur even if you don’t have a problem with yer keyboard:
You create several drum parts on different lanes. You decide to combine them together onto a single track. It might -easily- happen that there are overlapping kick drum or hat notes in random spots. Very hard to spot while a full drum set is playing. All you can tell is that there are -some- spots that just don’t sound right.
Same thing with string or brass… you start out writing several monophonic lines and then combine them onto a single ‘trumpets’ track. Certain notes sound ‘wrong’, so you keep fiddling with velocity or =whatever=, not realising that there’s -another- note behind the one you’re editing.
—JC