MasterCook can perform duplex printing even if you have a printer that does not have that ability.
Some printers can perform duplex printing. See this article: Print on both sides of the paper (duplex printing) in Word - Microsoft Support
MasterCook's duplex printing setting is turned on by default since many printers do not have that ability.
If your printer has its duplex printing setting turned on, it will conflict with MasterCook and prevent duplex printing from working in MasterCook.
So, you need to decide if you want
- MasterCook to do the duplex printing
- or your printer to handle it
It needs to be one or the other and not both.
The Microsoft Support article linked above explains how to enable/disable the setting for your printer. If you need further help with your printer settings, you need to contact your printer manufacturer or review their documentation on your printer settings.
The Flip Manually setting in the MasterCook print screen controls duplex printing within MasterCook. If you wish to disable the Flip Manually setting in MasterCook, go to the Print screen. Click on Long Side. Then remove the checkmark from Flip Manually to disable duplex printing in MasterCook.