Probably the issue is related to U+E000 to U+F8FF glyphs tab name - #2 by GeorgSeifert
Glyphs mini.
Why?
I don’t know. 
Because it happens only to glyphs with unicodes from E000 to U+F8FF as far as I can see.
Maybe you have a class with “unicode” and “name” property and you use “unicode” to display a tab name, but when new tab is opened you compare “name” property which is nil.
Ah i see. Sorry, I misunderstood your bug report as question.
I’ll have a look.
Update: It only happens to glyphs without a name or name like “uniE000” specified.
When I rename a glyph to something like “document” tab name is changed to question mark (which is another bug) and stops to be duplicated
Also, if there were more than one tab opened, all except one are named to “Glyphs” for some reason and become empty. I made a screen recording but it’s 36mb so I can’t attach it. Can e-mail it to you if needed.
I have seen that, too. Thanks for reminding me.
Fixed it.