The support portal for your printer says there is no driver for the OS Version you selected or the driver may be included in your OS or you may not need a driver.
Can't say for sure if a driver will be released, or if one is needed. The optional software applications won't guarantee 2 sided printing.
If you were running Mojave (everything working), then upgrded to Catalina, this might be the cause of your issue.
Here's what I would do.
Remove the device from printers and Scanners in System Preferences
If this is the only printer you have installed, go a step further and right-click in the printers pane, select Reset Printing System.
Now remove all installed Canon software compatible with Mojave OS.
Download any optional Software from the TS9120 Support Site (These are Catalina specific)
Install the printer again. I'd install using an IP address, and ensure you check the Duplex option when presented.
Following this, I would run any optional applications you might want.
If the duplex option was presented and checked, you should be able to print 2 sided.
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macOS v10.15 uses the built in Airprint driver to print with your PIXMA TS9210. The application that you are printing from, if capable, dictates what printing options are available. If Two-Sided is not an option, then that type of printing cannot be performed from that application.
For more informaton on the print interface, please refer to this link:
It doesn't make sense that this is dictated by the application, and I am certain that the application (in my case Pages) used to support 2 sided printing.
Also, the Pages help says this about the two-sided printing:
Print on both sides of the paper (also called “duplex printing”). This option appears only if your printer supports two-sided printing.
I think that this seems to suggest that it really is a feature of the printer driver?
I amn using a different Canon printer MG5320, but the problem appears to be the same.
Set up late 2016 MacBook Pro as new (after a repair), with Big Sur. Set up my Canon TS9120 printer. In order to print .pdf and disable two-sided printing, I had to un-✓ "Copies: Two-Sided" and also had to restart the computer in order for this preference to become set as default. When I simply un-✓'d "Copies: Two-Sided", without a restart, the .pdf document printed on front and back which is not what I wanted. Using PDFpen for this process. Updating the printer driver is my next step, just in case. But the restart helped the printer preference to set as the default in this case.
I have a MacBook Pro / Catalina with MS Word 365. I can print 2-sided (Duplex) files with Excel, PowerPoint and Adobe Acrobat Reader DC from my TS9120. The 2-sided option is not shown in the printer panel when printing an MS Word document. I have the current T9120 firmware and software updates installed. Word is also current. My workaround is creating a PDF file from Word and then printing. Time consuming. Any suggestions for a fix?
07/31/2023: New firmware updates are available.
05/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
04/20/2023: New firmware version 1.4.1 is available for EOS R3
03/30/2023: New firmware updates are available.
2/07/2023: New product announcements!EOS R8 EOS R50RF-S55-210mm F5-7.1 IS STMRF24-50mm F4.5-6.3 IS STMRF15-30mm F4.5-6.3 IS STM