When Bookdog automatically fixes a bookmark by giving it a new URL which it has received from a website, it temporarily keeps the original URL as a "Prior URL".
After the Verify process is complete and you click "Show" in the "Fixed by Bookdog" column of the Verify Bookmarks Report, Bookdog configures its Find window to search for all bookmarks which have a "Prior URL" and displays the Find window so you can see all such bookmarks which Bookdog has fixed.
If you would like to compare the current (new) URL and the Prior (old) URL, select a bookmark it and view the Inspector panel, which is also automatically opened:
If the Inspector has been closed, you can re-open it by right-clicking any bookmark (or holding down the ctrl key and clicking) the Inspector contextual menu item.
The contextual menu for the bookmarks in the Find window also has an item to "Swap prior and current URLs", which you may use to restore the Prior URL.
This also works with a multiple selection; i.e. you may select many using cmd-click and/or shift-click and the swap the URLs of all selected items with one click of the contextual menu.
Like any other changes you do in Bookdog, Bookdog's automatic URL changes are not saved to your hard drive or uploaded until you click Save. However, once you quit Bookdog, or if you re-run Verify, the Prior URLs are no longer available within Bookdog. In the latter case, the Prior URLs are deleted when the Verify operation completes or is cancelled.