I’ve had a rather frustrating few minutes trying to create a new category on one of my WordPress blogs and to name it specifically the way I wanted.
Why category slugs get -2
Every time I did this, I always ended up with the slag getting -2 added to it, and it took me some time to figure out why.
Turns out, you can’t create a category with the same slug that you have a tag for.
if you have a tag called “linux”, even though full link to it would be website.com/tags/linux, it will still prevent you from creating a category with the same “linux” name.
Page slugs for WordPress categories and tags cannot overlap
The reason for this is, apparently, because tags and categories share the same slug database table, so cannot overlap.
Hope this helps someone, it looked really weird at first but makes sense now.