I remember my brother winning a prize. He went to the bank to claim the prize, They offered him to either to cash the bond along with prize (Which he did cash out) or he could keep it. which suggests that same bond is being re-used (for keeping, trading and to be used again in the draw) but hard its to tell for any sort of markings that indicates that a bond has been cashed for prize.
They don't put any markings or stamp on a the bond which is cashed out for prize since...
1). You have to claim for the prize within 7 days after the draw.
2). You get the prize money within 15 days or a month or so... probably depends on the prize money.
3). The bank KEEPS the bond until they pay you the prize money. They keep the bond and return it (if you wish to retain the bond) with the prize money.
So if that's true, they don't really need to put any sort of markings or stamp on the bond to indicate that it has been cashed. specially, because of human psyche. It becomes much harder to re-circulate the bond when people see any cashed out markings or stamps, thinking it to be useless.