I'm pretty sure the keys are wired differently in the keyboard, but the question is what happens between the electronics and the passphrase software... there may be a layer somewhere that declares them similar. Then again, you want as little layers as possible for passphrase code in order to make it more secure.
There is a command line program "showkey" that will show what key is pressed. The X11 equivalent is "xev". I can't try them here b/c I only have access to Redhat via ssh at the moment.
In any case, I'm pretty sure it's not a good idea to have a key like that in your passphrase. What if your keyboard breaks and your new keyboard does not have the same key? Better to use the normal exotics