The CrashPlan app ties every backup archive to its source computer with a unique computer ID. When you migrate the CrashPlan app using a program like Migration Assistant or Time Machine, the file containing this unique computer ID is transferred from the old computer to the new computer.
As a result, both computers share the same identity. Changes made in the CrashPlan app settings on one computer (for example, the computer name) also update on the other computer. Follow this troubleshooting article to assign your new computer a new ID and differentiate the computers for the CrashPlan app.
The CrashPlan app on a Mac using Migration Assistant or Time Machine.
Perform a complete uninstall and reinstall of the CrashPlan app on the new device.