The 1st disc is actually from 1845-1869 not 1845-1865 like the disc jacket reads and so when you put in the 2nd disc, half of the 2nd disc is an exact duplicate of the 1st. I also noticed that the 1st disc is by The American Experience. All the other discs have a different label. That may be why there is a mix up.
It is an excellent production, though, and very informative.