certified cheque

This is US law, maybe Canada has different rules, but:

https://www.sapling.com/8611754/do-void-certified-check

But the New York Credit Union Association cites §3-403(2) of the UCC. This section indicates that payment can be stopped on a certified check if ‌90 days‌ have passed since it was issued ‌and‌ the check has been lost, destroyed or stolen. The remitter would have to submit an affidavit to the bank or credit union in this case and request a stop payment order in writing.

The CP admitting that they lost the check should suffice as evidence that the cheque has been "lost, destroyed or stolen".

Imagine a bank robbery and the robbers demand the tellers issue a bank draft / certified check to the robbers actual name.

At the end of the robbery the bank has, a serial number of the check, the payer name.

It would be silly to expect this bank to honor this bank draft / certified check. They simply wouldn't do it.

So the rest of the "we can't prevent double spend of this bank draft", is silly. They can verify the payee, pay the draft and cancel the original draft by serial number.