In the community, a "1 of 2" designation usually refers to a two-part volume set or a split catalog. Because the 2004–2012 output was so massive, many archives and private collections split the inventory to manage the data or physical storage.
To help you find exactly what you're looking for, could you tell me: Modelers unique - MODELIK 2004-2012 1 of 2
If you have obtained this specific file set, you are not a casual hobbyist. You are an engineer. Here is how to handle the 2004-2012 MODELIK "unique" aesthetic: In the community, a "1 of 2" designation