Adwaita icon naming

I was looking at the naming of the symbolic icons in this theme. I noticed that the png icons end in -symbolic.symbolic.png. This seems quite excessive, since that’s two times symbolic in a row. The svg icons only have -symbolic.svg. Is there a good reason for naming them like this?
This naming has been introduced recently and it breaks my application (dunst, Users now have to specify for example “dialog-information-symbolic.symbolic” instead of “dialog-information”. I don’t think other icon themes name their icons like that. I could add -symbolic.symbolic.png and -symbolic.svg to the list of different file extensions, but it’s not defined in the standards. So this seems more like an adwaita bug.

Gitlab issue (closed):

It’s not a bug.

The symbolic.png extension is for a specially crafted PNG file that can be recolored like the symbolic SVG file; see:

The idea is that themes can ship these additional files, and GTK will load them without requiring the SVG loader.

This should not be necessary at all: the handling of symbolic.png is internal to GTK. Applications should use dialog-information-symbolic everywhere that matters.

The entire symbolic icon support is essentially unspecified because nobody has taken up the time to update the icon theme specification to include it, so it’s fundamentally a GTK extension.