Database |0 contains a site (Id = |1], Url = |2]) whose url is already used by a different site, in database (Id = |3], name ...

Database [|0] contains a site (Id = [|1], Url = [|2]) whose url is already used by a different site, in database (Id = [|3], name = [|4]), in the same web application. Consider deleting one of the sites which have conflicting urls.