My take on this, there are Mark Carney $5 polymer notes.
When these notes were released, Stephen Poloz launched both notes earlier this November. To give him some credit for the launch, the Bank of Canada decided to issue $5 notes bearing his signature. Considering Poloz is the head of the BoC, it would have been awkward to have Carney's name on everything, including the big blow-up cardboard scans of the polymer notes, and on the physical notes at the official launch date.
It will just be a matter of time for the Carney/Macklem $5 notes to appear. The possibility for the Bank of Canada to have destroyed the new $5 polymer notes for just having Carney's signature would be a publicity nightmare for the government, for wasting taxpayer's money. If Carney's signature was that offensive on the new notes, then the Bank of Canada would have not distributed Carney's $10 polymer notes.
I think, and it's my opinion....when Carney unexpectingly announced his resignation, and after some time to find his replacement, Poloz eventually got the top job. I believe the Bank of Canada decided to change course with production and focused on getting $5 notes bearing his signature, instead of the $10 notes for the inaugural launch by Poloz himself.