If it actually went down like this, that's pretty horrible, and that someone else is a grifter. Very harmful for any organization in the long run, because that behavior will be applied to anyone who's "ripe to be taken advantage of" (from his point of view), burning them out of the way.
That is, if they were aware that you made the thing that they picked up later. Though I wonder why the original didn't go through. The other person pushed harder for it to go through, or showed it off with a different sort of demo? Or was it a different sort of technical implementation / design?