MusicXml - Lyric sylable output twice

There are times when I will use hidden grace notes after a note to have hanging ties (notably with voltas).
I have just come across the occasion when, if I have a syllable under the note, the MusicXml output will reproduce the syllable under it AND under the grace note.

Example attached :
The first bar is the volta which redirects to the beginning (though I may have omitted to put the D.C. or a repeat bar).
When looking at the exported MusicXml, you can see the repeated lyric syllable in the grace note node (line 190 onwards).