Issue:
when using advanced copy in the Content Manager to duplicate a number of
similarly aliased pages, the new aliases aren't renumbered corectly

To recreate:
-create a few pages with the aliases test-1, test-2, test-3
-select these pages then use the advanced copy bulk action
-leave everything as defaults and submit
-the resulting pages will all have the alias test-4

Expected behaviour:
resulting pages should be aliased test-4, test-5, test-6 (or test-1-1, test-2-1,
or copy-of-test-1 or whatever, but the first option would be nicest)

Workaround:
re-alias the pages manually, either during the copy process or after