Is it possible for one keyval to have multiple keycodes?

[Cordylus Interneter <cordylus zoho com>]

I'm trying to detect in a layout-independent way that some key was pressed. My plan is to convert, say, 
GDK_KEY_A to keycode on program start via gdk_keymap_get_entries_for_keyval and compare 
event->hardware_keycode with it on key-press-event. My questions is: is it enough to get only one keycode 
from the first entry of the GdkKeymapKey array returned from the gdk_keymap_get_entries_for_keyval, or do I 
have to save all possible values and check for them all? What if there will be a USB and a PS/2 keyboards 
connected? Will there be different keycodes in that array? What about different platforms?