Agent WranglersAccessibility Required
Never ask for the same thing twice
Never ask people for the same information twice in one process. Fill it in for them or let them pick it. This is WCAG 2.2 criterion 3.3.7 (A).
How to do it
Carry entered data forward through a process. Offer "same as above" choices. Re-entry is allowed only for security, such as confirming a new password, or when the old value is no longer valid.
Example
<label><input type="checkbox" id="same" checked> Billing address same as delivery</label>
<fieldset id="billing" hidden>…</fieldset>How to check
A browser test walks every multi-step flow. Any later field asking for earlier data is filled in or offers a choice.
For agents: if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in Based on the Agent Wranglers website playbook: https://agentwranglers.se/playbook/website/accessibility/redundant-entry.