It’s the underscore that’s causing the problem. It doesn’t seem count as a valid “word separater” for tags so “Conrad” and “stargard” are counting as two different tags. You can see this even more clearly if you press space after the tag it converts the underscore to a hyphen.

In fact even if this wasn’t standard behaviour I would suggest you always use hyphens instead of underscores in tags so it keeps everything consistent across the site.

It’s the underscore that’s causing the problem. It doesn’t seem count as a valid “word separator” for tags so “Conrad” and “Stargard” are counting as two different tags. You can see this even more clearly if you press space after the tag and it converts the underscore to a hyphen.

In fact even if this wasn’t standard behaviour I would suggest you always use hyphens instead of underscores in tags so it keeps everything consistent across the site. Actually looking a bit further the tagging guidelines on main meta even state you should use hyphens in place of spaces.

Replaces spaces with dashes (-) to combine multiple words into a single word (i.e, Tag "Unit Testing" as "unit-testing").

FWIW I can't find an explicit post about the changing of underscores to hyphens in tag names, only this one about improving that feature but it should be enough to prove this is what happens.