How can I merge two ddrescue images?

I have two ddrescue images created from sequential recovery attempts of the same media. The two images are the same size but have complementary data: $ od part-one/ddrescue_image --skip-bytes 227966006774 --read-bytes 32 3242365232766 113056 016517 102014 074371 144073 000000 000000 000000 3242365233006 000000 000000 000000 000000 000000 000000 000000 000000 3242365233026 $ od part-two/ddrescue_image --skip-bytes 227966006774 --read-bytes 32 3242365232766 000000 000000 000000 000000 000000 124616 163450 064251 3242365233006 074567 134433 012742 022160 044301 054235 140604 020633 3242365233026 How can I merge them into a single, complete image? ## Details - The second image is simply a continuation of the first recovery attempt, à la: $ ddrescue corrupt-partition part-one/ddrescue_image part-one/ddrescue_log $ mkdir part-two; cp part-one/ddrescue_log part-two/ddrescue_log $ ddrescue corrupt-partition part-two/ddrescue_image part-two/ddrescue_log - The second image is almost entirely zeros, but contains 18 KB of recovered data spread across 1847 isolated regions. - I tried using the technique mentioned on this mailing list , $ ddrescue --domain-logfile=part-two/ddrescue_log part-two/ddrescue_image part-one/ddrescue_image part-one/ddrescue_log GNU ddrescue 1.16 Press Ctrl-C to interrupt Initial status (read from logfile) rescued: 937286 MB, errsize: 62976 B, errors: 122 Current status rescued: 937286 MB, errsize: 62976 B, current rate: 0 B/s ipos: 0 B, errors: 122, average rate: 0 B/s opos: 0 B, time since last successful read: 0 s Finished but it doesn't appear to have changed anything.