Steps to reproduce

1. Create a page with title that contains a hyphen. Example : hello-world
2. Create a few anchors by inserting the Table of Content macro into the page.
3. Copy the anchor URL and paste it on another Confluence page.
4. Click onto the pasted link and you'll be directed to a broken anchor on the page.

Cause

The anchor is broken because the word after the hyphen on the page name is duplicated twice in URL.

Example for hello-world page. The word world is duplicated.

http://localhost:8090/display/S/hello-world#hello-world-world-what

Workaround

1. Do not use hyphen in the page title
2. Remove the duplicated word after the "#" in the URL and the anchor link should work fine (Tested on Confluence 6.3.3)