If you normally try to copy or startup another entry that is configured as a cache, it would error out saying the cache.db or something along those lines is already active.
For my rclone moves/etc/such, I do not use a cache entry in my rclone.conf
I basically have GD->Cache->Decrypt for my cache mount.
For rclone copy/sync commands, I use GD->AnotherDecryptName with the same passwords as the first.
So if I run a rclone move, I use the second item and if I’m mounting, I use the first.
Anything copied should get picked up on the cache via polling as the default interval is 1 minute.
In your case, you can you sync to go from GD1->GD2 and I’m guessing on GD2, you want to to the GD2->Cache-Decrypt and mount the decrypt.