According to embodiments described herein, a backup server maintains backup data for a set of data, which includes data for a first block and a second block. Backup data for the first and second block include backup data for a plurality of versions of the first and second block. A distinct watermark is stored for each version of the first block and each version of the second block. In response to a request to perform a restoration operation on the set of data, a particular version of the first block and a particular version of the second block are selected to use in the restoration operation by comparing a restoration target with the watermarks of the version of the first block and second block. The selected version of the first block has a different watermark than the selected version of the second block.