Tons of times i had to advise folks to **install** an independent OS for emergency booting. Booting into the same "exact" OS that we want to repair or restore is problematic. I always use SuperDuper to clone my main drive and have never had a problem repairing it with either DU or DW when booted from the clone. I have never tried Ditto so I can't comment.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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