Steps to reproduce.
1. Edit an existing page from Page Setting (note down the sequence of the sort order of that tab)
2. Click Save button
3. The page is re sequence at the end of all the pages. sort order of the tab is updated as max(sortorder) +2 of the tabs under the same parent
The root cause is that the page is MovePage() is being called even when the old parent id is the same as the new parent id. So the tab's sort order is always updated regardless. Please check the attached for the suggested fixing.
Please note that the suggested fixing should be on top of the suggested fixing on the reported issued DNN-10757.