Your HomeDrive dashboard is uniquely identified, and the encryption keys are stored locally on your machine. Therefore an IMG file can not be used for two different installations.
HomeDrive stores your files in a local, encrypted file. Moving this file to another PC would require the decrypting/encrypting algorithms and is beyond the scope of HomeDrive's functionality. Copying the IMG file could result in serious syncing and security issues, to move your data to another PC you have to import your account and Vault on each computer you wish to synchronize.