This is a form hidden with display none:

This is the same form not hidden and with the same IDs as the first.

While duplicate IDs in of themselves are no longer a failure under WCAG 2.2 §4.1.1, this page illustrates how duplicate IDs can lead to unexpected results. When multiple elements have the same ID, references to that ID will always pick up the first instance in the DOM. In this case the first label that is hidden by display:none will be assigned to the second form such that the visible label will not match the spoken one.