ID attribute values must be unique.
As implied by their property name,
id values should be unique regardless of their accessibility.
Labeling interactable elements is an important part of accessibility and many labeling techniques use
to link the labeled and labeling elements. When
id values are not unique, it might cause confusion and
misunderstanding with the UI by screen reader users.
How Users Are Affected
Screen readers will only refer to the first element with a certain
id and skip each additional
element with the same
id. The user will therefore not receive the full content.
WCAG Success criteria
This issue might cause elements to fail one or more of the following Success criteria:
4.1.1 Parsing (A)