Unwanted outlines on "invisible" font

Hello there.

This is my first ever involvement in this forum. I might not be fully accustomed with the order of things in here, so if I can do anything better please let me know.

I created this variable font with the letters doubled and reversed on each other, so that its essentially invisible. On additional masters I can then drag out the duplet, which creates a shadow, thus making the font visible.

The problem is after exporting, the font know has outlines which wasn’t there in glyphs. I’ve tried inspecting the font on Samsa, and it still creates outlines ( see bottom left picture )

Does Glyphs create these outlines upon exporting?

The outlines are the result of rendering two overlapping shapes. I’m pretty sure there is nothing you can do about it. Glyphs uses a different renderer that is close enough in most cases …

Thanks for replying!