Cups automatic duplex printing problems

Hello list,

I'm having printing problems under Linux, with several printers, and I'm 
not sure how to proceed. It boils down to:
- I cannot print duplex on autodetected printers;
- I cannot print multiple copies on manually added printers: whatever I 
try, the printer says it is a duplex job with just one page to print.

With some help, I'm probably able to debug some of the problems, but I 
actually sort of lost track with regard to printing - there is 
cups-browsed (which adds printers?), cups-filters (does that do anything 
anymore? Or are these driverless-printers just bypassed?), cups itself; 
then there are manufacturers that send out printer drivers that look 
like PPD's to me - that should not be necessary to include anymore, 
right? Driverless printing is just what it says, driverless?

This is under: Ubuntu 22.04
Cups 2.4.1op1-1ubuntu4.7
Cups-browsed 1.28.15-0ubuntu1.2

I hope this very new list can help me to become informed again and debug 
simple printing problems :-)

Best regards,

Valentijn