well, it could have been someone that changed their "race" in-game (which only changes their appearance) and other races may have more head appearances than halfling/gnomes.
lets just say for an example, lets say there are 14 human heads sets. and there are 9 halflings, if the person chooses human 10-14... they will become headless in halfling form (remember, this is not the true number of heads, its just an example)
so they become headless. talon may also want to look into making a player list on the sent rune which allows the sent to select anyone they choose on the server...
info and an idea =D