Apple Configurator 1.4 uses an improved database with a new format. When you open Apple Configurator 1.4 for the first time, your current database is migrated to the new database and a backup copy of your old database is moved to the Previous Data folder:

~/Library/Containers/com.apple.configurator/Data/Library/Application/Support/com.apple.configurator/Previous Data/

Note: The Previous Data folder also contains a Resources folder, which includes apps, device backups, user backups, documents, and IPSWs. Before migration, Apple Configurator moves backup copies of certain resources to this folder. If you discover that resources are missing from your upgraded database, look for them in the Resources folder.

If migration is successful, you can safely delete all storedata files in the Previous Data folder. Apple Configurator 1.4 will not use them again.