Yellow triangle warning

Hello. I’m getting a yellow warning triangle for a style set feature: The font contains glyphs with the same name: .ss06.
There are no repeat glyphs with the same name within the font, and they are not showing in pink for the usual warning within the feature window.
I can’t understand what the problem is.

Can you please send me the .glyphs file to support (at) (this website without ‘www’ or ‘forum’). I will have a look.

Done.

Somehow you managed to get two glyphs called “.ss06” into the font:

Thanks very much. I don’t know where they came from.