On Thu, 14 Feb 2019 08:12:59 -0600, David Harper wrote:

I have used several different all-in-one printers over the years (mostly
Canon). They all did two-sided printing the same way: print the odd page
numbers first, then ask the user to take those printed pages and turn
them around and put them back in the input paper tray to have the even
numbered pages printed on the back of the odd numbered pages.

My latest, cheap Canon all-in-one printer, MG3600, does it differently
in a way I can't figure out how it does it!

This new printer when printing double-sided will print page one, then
pull the page back into the printer and print page 2 on the back of page
one. How does it do that?

Probably in a similar way to the duplexer on my old HP. Suck the page
back in, then run it to a holding area (probably round a roller), then
back into the input area the other way up.