As I was making some custom textures, I noticed that after retexturing CustomModelData:101, items with the CustomModelData:102 tag have the texture of 101. I don't know if that's intended but its misleading when one of your custom textures fails to load and you see some other texture.

To reproduce

1. Use the example.zip pack
2. Give yourself the following three items:

   # shows diamond, since custom model 100 is not defined
   give @s minecraft:diamond{CustomModelData:100}
   
   # shows emerald, since custom model 101 has been defined
   give @s minecraft:diamond{CustomModelData:101}
   
   # shows emerald as well, even though custom model 102 is not defined
   give @s minecraft:diamond{CustomModelData:102}