All sorts of name problems, yes. The name on this case sounds like the Spanish style name where they take one name from each parent. In those cases, there are two last names but people are often confused how to write them.
In terms of numbers, I suspect I have told people to correct their names on the DS260 (i.e. different to the entry with various errors) literally hundreds of times over the last few years. I rarely hear from someone subsequently denied for the name issue, and if I do, it is typically from one of the "tougher" embassies (dealing with high fraud levels).
Similarly dates of births are often messed up (somehow people don't know their date of birth, or convert the dates wrong, or get birth certs and find they have a different birthdate than they thought). Again, the advice I give is get it right on the DS260 - and again, not many cases come back saying that advice didn't work.
Now, any time I give advice that doesn't work, I do generally hear from people. They are always generous with that feedback. So - I am pretty much certain I would be hearing from MANY more people if advice about correcting the name was failing.
