When I connect an additional keyboard (docking my laptop for example), keyboard settings like repeat speed and delay fail to apply to the new keyboard. Worse, it also seems to reset these settings for the other keyboard!
This is already fixed in git master but will generally not make it into distros until xfce 4.12 is released. Until then, you should probably try to use xfce-xkb-plugin to manage keyboard layouts (the latest version for xfce 4.10 is 0.5.6 and it shouldn't have this issue).
fixed