These records are typically found in the radio broadcast realm. They were used to send out syndicated programs such as the Jack Benny show on these large LP's. They arrived with one side recorded so that they could play the show on two players and fade them from one to the next. The records were also recorded from outside in and then the next from inside out to avoid the pitch difference that would result if they had to jump from inside to outside of the LP's. Dennis Duffy showed me some of these records at the BC Archives. The stations used the back of the records to record commercials. SPARC here locally has old radio broadcast equipment.

http://www3.telus.net/radiomuseum/visit/index.html#membership

One of the SPARC directors in Kelowna has a player for transfers, so does BC Archives, and CBC Vancouver.