Contains duplicate element id values
This means that the URL in question contains DOM elements with duplicate id attribute values.
Why is this important?
What does the Hint check?
This Hint will trigger for any internal HTML URL that contains DOM elements with duplicate id attribute values.
Examples that trigger this Hint:
For example, the following HTML document contains two li elements with the same id:
How do you resolve this issue?
Even if it may appear that browsers can handle pages with duplicate ids, there are lots of very good usability and accessibility reasons for using unique ids, so ensure that all duplicate ids are renamed to be unique and unambiguous.