I've created some tag types and instances of them, but when my project loads, I get a "Tag name collision" in the Error Report.
I've checked the help files and it mentions that the duplicate tag will be disabled, but both tags in the tag browser are enabled, and further to that, the names of the tags and the unique IDs are all different. The only thing that is the same is the "declaration key".
Am I missing something?

I tried disabling the one instance and noticed that what was the "Tag name collision" was referring to was actually the "Started tag name" and "Stopped tag name", referring to the exact same tag.
I'm a bit confused, as I don't know what the difference is between "Started" and "Stopped" tags. The (single) tag in question is enabled.
Any ideas as to what to look for?

I see what's going on now. The "Started tag name" is the first tag with the same name that was started. The "Stopped tag name" is the duplicate tag that wasn't started (as outlined in the help file). I misunderstood how they were being presented because there were two separate entries.
Once I deleted the unwanted duplicate tag (which was the one that was started), Redefined Type, stopped and restarted the project, everything was fine.