Hyperlink window > New Hyperlink. Then I choose the kind of link I want and there is a checkbox with the option of selecting "shared hyperlink destination". What is this?
The Help file for Hyperlinks explains it:
It's to make hyperlinks used repetitively to be called out easily. It sometimes caused problems if you're using InDesign CS6 or earlier. It was fixed for the most part in InDesign CC and later: