I have in my collection an alternate release of this: Symphonie Nr. 8 c-moll (Erstfassung).
The only differences between it and the version I own is the catalog number, and that my copy is one CD, whereas the above is two CDs.
I’ve been trying to create an entry for the release I have, but when I add the existing medium it keeps it as two CDs. How do I combine them into one CD?