For every gene, there are typically at least 3-4 names that reference the gene. In some cases, two genes have the same name- for example, OCT1 and Oct-1. The first is "organic cation transporter 1" and the second is "Octamer binding protein 1". The second was "renamed" to (IIRC) POU2F1 but there are still plenty of references to the old name even in new literature.

This is just one example. The entire gene naming area is a pile of bollocks.