I use xmodmap to change from us keyboard (xmodmap.us) to quebecois keyboard (xmodmap.qc). when i switch back, from quebecois I enconter a strange bug, some keys doesn't work anymore, and the numlock key have a strange comportement, the light was always off, but the numeric keyboard was always on except for the dot (.) whom doesn't work anymore. You don't put xmodmap in the listing, so I choose enlightenment, this is the WM I use under X. I don't use GKB-Xkb, because event if you have the Quebec's flag on it and the qc keymap, it's simply don't work, and it don't remember the configuration :-(
Just changing the component.
I think the main problem is that the xmodmap files are not intended to undo each others changes - you need to pick one and stay with it. I can produce the same behaviour, but this is in the "so don't do that" category, I think...?