This dialog is displayed when you try to decrypt a Destination that has been fully or partially decrypted before. Disk Recoup will display the sector number following the last decrypted sector.
From the beginning to ensure complete decryption.
Scans the Destination from the beginning and decrypt sectors still in encrypted form. Sectors already decrypted will be skipped. This option will take more time but ensure all data is decrypted.
From the sector below
Resumes decryption from the sector number displayed. In a normal situation, this option should be chosen.