@Tony: No, you can not use them as postage, because the are already used.
It is always the same discussion; are CTO used or not?
My opinion is always: Yes, these stamps are used, because you can not use them again for sending a letter.
@ Jessica: Maybe it was a mistake from the sender, because of lots of fishes :)
If you will get my address again, you can send them to me :)
Jessy, be generous, give a 3 :)
Happy Easter.