Non-unique accesskey attribute
Page-specified shortcut keys and accesskeys MUST NOT conflict with existing keyboard shortcuts in the browser, operating system, or assistive technologies.
If a page-specified shortcut or accesskey conflicts with an assistive technology like a screen reader, the screen reader will generally override the shortcut or accesskey, making the custom shortcut unavailable to screen reader users. When page-specified shortcuts or accesskeys are created for a web page, those shortcuts and accesskeys must not interfere with keyboard shortcuts used in the browser or keyboard shortcuts used through assistive technologies.
Fix this issue by ensuring all accesskey attributes on a page are unique.