Them being poured bars was a rather significant fact you were totally missing in the original post..
You're very right. I have been dealing in bullion (especially silver) for a while and I had never come across or even HEARD of 1oz hand-poured Engelhard bars. I did a lot of looking and this was all I could find:
http://about.ag/Engelhard-1oz.htmHand-poured 1ozers have to be among the rarest Engelhard products ever made-if they were truly minted by Engelhard. That I am curious about. The pour on the pictures of these is pretty terrible. I pour my own silver with a MAPP gas torch, a poor man's crucible and wood molds I buy at the craft store...they end up looking A LOT better than that. I find it difficult to believe that Engelhard would stamp such a bar with their logo (due to their respected status). Also, nearly ALL Engelhard bars ever minted have a serial number on them-these do not. I am not necessarily accusing OP of "foul play", but it would be very easy for the Chinese to produce a "hand-poured", make an Engelhard stamp and stamp it. All things considered, I would stay away from these-even though the idea of a 1oz hand-poured Engelhard bar is pretty cool.