The discs are labelled funny. One disc has sides 1 and 4, the other has sides 2 and 3. 
Actually not funny at all.This was a pretty standard way of issuing 2 LP sets back in the 60s. The sides are laid out this way so they can easily be played on a stacked record changer.
Side one would play and then the changer would drop the second LP and play side two. You would then flip over the stack and play sides three and four the same way. There were also similar patterns for LP sets with higher numbers of records such that the whole set could be placed in a stack and the sides would automatically be played with the user only having to get up once the flip over the stack and start the changer again.
Damn I feel old explaining this. I wish I could say that I just know this from reading about it, but my first turntable (bought from profits from my paper route) was a Model 42M Garrard changer.
It is kind of funny looking back that I somehow found a short single LP spindle and replaced the taller automatic dropping spindle because I was afraid that dropping a record on top of another already spinning record might possibly cause damage to one or both of them. Holy cr@p, I didn't realize it, but Nervosa was nipping at my heels all the way back to my preteen years.
