In the Single Object Compare window some buttons are disabled. (“Copy to Left” and “Copy to Right” , “Open Files”, “Delete left text” and “Delete right text”)
As a result, it's not possible to merge scripts with Toad.
Get the script for the objects from the Schema Browser, save them to files, then compare the files. Then you can copy right or left
Waiting for fix in a future release of Toad for Oracle