I think they are different as I've had a few from both formats

Totally agree. There was another post about this a week ago you may want to read https://help.trademe.co.nz/hc/en-us/community/posts/14983776839695-New-Fixed-Price-Offer-emails  

Alternatively you can set your stock level to 0

Your question was how do you remove mfa from Trademe. My instructions is how you do it?. Can you not get it from your old phone?

Yes you need to put in your code to continue

Click on my trademe (top right) then scroll down to "update my details" to find the MFA area. Click through from there to remove. This is on the desktop site

When I duplicate an item, the shipping details also carry through to the duplicate listing - is yours not doing this?

And don't ship the item until you have full payment including the postage costs.

Hi gwtm33 Callum's advice about getting the buyer to bring it back to check is good. In my experience, too many people these days claim something doesn't work either cause they aren't using it properly OR they are trying to get it free/cheap. I always insist on it being returned prior to any refunds so I can check. Funny how the problem goes away when you ask for that    

Thanks S!