Well if you ever get to the bottom of this, I’d be curious to hear more! 
It seems strange to me that you would need to “re-use” a label, because I have added non-standard entries myself. For example, I use an xbox 360 DVD remote (Xbox 360 DVD IR remote multiple repeats - #6 by DBMandrake), so I added actions for the “xbox” logo button.
In lircd.conf, I added:
KEY_VENDOR 0x0BF2
In Lircmap.xml, I added an xbox key (which did not exist anywhere else in the file):
<remote device="linux-input-layer">
<altname>cx23885_remote</altname>
<left>KEY_LEFT</left>
<right>KEY_RIGHT</right>
...
snip
...
<teletext>KEY_TEXT</teletext>
<clear>KEY_DELETE</clear>
<xbox>KEY_VENDOR</xbox>
</remote>
And in remote.xml, I defined xbox actions (where “xbox” again was new here):
<keymap>
<global>
<remote>
<play>PlayPause</play>
<pause>Pause</pause>
...
snip
...
<print>Screenshot</print>
<xbox>scanitem</xbox>
</remote>
</global>
Other than the global section, I also further specified xbox actions depending on which screen I was on (i.e. update Music library, when in Music window; update Video library when in Video window)
<MyMusicLibrary>
<remote>
<zero>Queue</zero>
<star>Queue</star>
<xbox>UpdateLibrary("music")</xbox>
<record>PlayerControl(Partymode(music))</record>
</remote>
</MyMusicLibrary>
<MyVideoLibrary>
<remote>
<zero>Queue</zero>
<clear>Delete</clear>
<xbox>UpdateLibrary("video")</xbox>
<record>PlayerControl(Partymode(music))</record>
</remote>
</MyVideoLibrary>
This seems to work fine for my remote.