I believe this dealer has some good stuff, some very good stuff, some marginal stuff and some no way stuff. An interesting mix of a collection for sure.
As far as reproductions go, the only "reproduction" item I have is a brand new civil war type cloth haversack I take into the woods detecting with me. Used it today at the beach. Great for dumping a lot of stuff into fast in situations where a speed basket isn't practical.
And before anyone can reach a conclusion by a photo, the plate should be measured and matched or not matched to an existing plate already documented in some of the Civil War reference books. At this late stage in time, it would be highly unlikely a one of a kind plate will surface, but still, it remains possible. I always ask for specific dimensions on plates and up close pictures, especially of the back and the sides if possible. I have only bought a few plates ever, either Union or Confederate or Rev War, and they have come from the major players out there so I have complete confidence in them. They weren't cheap, either. I just hope the market goes back up, it's been soft for almost 10 years now.
Then I get my $500 in text books out and let my fingers do the walking. Also there are a lot of dealers out there who just pass stuff through their sites or Ebay and really don't know what they have. Some of the early reproductions are very hard to tell from the originals, in all fairness.
Fortunately, I don't have to sell what I find.....
Just for fun, as I am not an expert on plates, I dug out my better textbook. This plate was not made as a cast plate at all. It was stamped rolled brass, much thinner with a totally different back.