When there are duplicate pages, a number is added at the end of the page. However, when editing the path, the number is not displayed in the page's path, resulting in an offset in text equal to the length of the number.

For example, if it should be like this:

mysite.com/index.php/mypage


But the page is actually being rendered as mypage1, it will show in the Properties window like this:


mysite.comindex.php/mypage



Or sometimes it works the opposite way:


mysite.com/index.php/mmypage



The only way to fix this is to delete the conflicting pages, rename it to something weird, like "mypage20", then name it back