It is an error in the Footprint itself.
In KiCad it is legal, (and common) to have multiple pads with the same pad number to make big or complex pads. For examples for this, search through KICad's Footprint libraries for any footprint with "thermal" in it's name.
Your situation is different though. For most footprints, the shape of the paste and mask layers is derived from the pad itself. For some footprints though, the solder paste or mask have a different shape, and in such cases a different pad is used, but with it's copper layer turned off. I believe these are called "aperture pads" in KiCad. These pads are however not allowed to have a pin number. The pin number string must be empty, and this is not the case in your footprint.
You are also using quite old libraries. The plural form of
Housings is a strong indication that this is a library for KiCad V4.
The closest match I could find in a KiCad V5 library is:
> Package_BGA:Texas_DSBGA-6_0.9x1.4mm_Layout2x3_P0.5mm
And in this footprint the error is corrected. The pads for the F.Paste layer does not have pin numbers.
So the next question is:
Are you aware you are using an old library or has this just slipped your attention?
This may be relevant for you:
https://forum.kicad.info/t/i-had-kicad-4-installed-previosly-now-i-updated-to-v5-now-i-have-some-problems-with-the-library-setup/11932