I think it used to be more of an issue before they came up with the common databases, and as someone stated it usually gets worked out eventually.
Many of them are just simple misspellings. I've mentioned I have a brother that has been in and out of the system for years. (meth and all the thefts that come with it) Mom and I have come to an agreement to just not discuss him, because we don't see eye to eye
so I sometimes get curious and look it up online. Sometimes when I sleuth his records I find that they have misspelled his last name (changed one letter) and he goes by his middle name, so I often see his first and middle names swapped. Mr. Middle First Last. Or Middle (first initial) Last. It's just someone screwed up when they entered the info.