Rudolph Pelck was a mid 19th century gunsmith from Freeport, Stephenson County, Illinois.
Could you possibly post some more pictures?
Right now I would be assuming, but I would bet that the hammer and drum on the left side are offset from the one on the right....it appears to be forward of the right one in the picture.
If that is the case then what you have is a fairly rare duplex load rifle. The gun would have been loaded with conventionally with a charge and tightly patched ball and then another on top of it. The gun would be fired front load first of course.
Very interesting....and, again, rare! Thanks for posting. Enjoy, J.D.