1. This is on purpose. It is a very long discussion which I will try to sum up. The UID field is supposed to contain a "unique identifier". This is used in RSS and Atom feeds so the reader software knows to NOT include articles it has already seen. WordPress completely misunderstands the specification and uses the URL of the post as a unique identifier.
THIS IS WRONG. However, we MUST not change it because that causes SEO issues on the restored site. In fact, we used to change that and we received complaints from people. That's why it's not replaced anymore.
What should have WordPress done? They should have used a
UUID instead of a URL in that field. I am told there are third party plugins which do that but I've used none of them so I can't recommend any.
2. You can address it at restoration time by adding a rule with FROM set to http:%2F%2Fold.url%2F and TO set to http:%2F%2Fnew.url%2F. It would help me plenty to know which plugins caused records like this. I want to double check they should be replaced before adding these as default replacements in the restoration script. I have had really bad experiences with the crazy things some plugin developers do with data in the database :)
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!