Hi 1mcgeek! Thanks for posting in the Canon Community Forum. I see that your Canon PIXMA TR4720 is not printing double-sided when printing from an iPhone.
I see that you have tested the Two-Sided printing with a Windows computer, and it is working from your computer. As long as you have the “Double-Sided option) in your AirPrint settings turned on, it should do the same thing. Since it is not, I recommend looking at the other settings.
The first setting I would check is the Presets at the top of the settings window. Please make sure it is set to none. If you have it set to another preset, it may override the double-sided selection. You should also check the paper size setting as double-sided only works with certain sizes. Please make sure it is set to Letter.
If that is not helping, please check if Color is turned on and if the scale is set to 100 percent. If they are, please see if the double-sided option works with a different document. If the settings are not the issue and the double-sided option is not working with other documents, I recommend contacting Apple to check why the double-sided option is not working on your phone.
I hope this information helps. Thanks for choosing Canon
