Having received several cards with the stamp not franked is it alright to use it as someone told me once that they are still franked but you just can't see the frank mark.
As a ex postie flitty i have not heard of this one before, some times mail can go through the franking machine stuck behind another letter, so it will miss getting stamped, if you were to get this off the letter and stick it on another envelope it could drop off or it could be noticed at the delivery office in either case the person you are sending it to will have to pay a surcharge, i think this is £1 plus postage
Just to add one more thing to this thread, you may have seen the stamps that you peel off a backing then stick on the stamp, without licking if you pull these off the envelope it leaves two small pieces of the stamp on the envelope and obviously two holes in the stamp. If you then reuse the stamp the machine will reject it and then the letter surcharged
Use them again, no problem. On the subject; I once knew a man, a clever artist (now deceased alas) , who first thing on the morning of issue of a new stamp would buy the stamp and spend the rest of day painting an exact scale replica which he would get posted back to himself by the last post, thereby owning a first-day cover forgery, apparently in the world of philately forgeries are collectors items.
Very clever khandro I would loved to have seen his work, it most have been good I am surprised it got back to him as a fdc, perhaps the local office knew of him and let it go.
Eddie I have looked at the ebay thread and the stamps appear to be stuck on envelopes, so as I have explained if they are the new type they are useless