Hi @Malypense,
Good Day. A warm welcome to the HP community. I reviewed the post regarding assistance to print double sided and single sided at the same time. I will be delighted to assist you here.
Splendid description and great observations made before posting. Kudos to you for that. 🙂
I will not beat around the bush here. The setting to incorporate both duplex printing and single-sided printing simultaneously is not be available as a feature of either the operating system or the printer.
Here are a few links that will assist you with duplex printing.
Link 1 HP Printers - Printing on Both Sides of the Paper (Mac) (Duplexing): https://support.hp.com/us-en/product/hp-envy-120-e-all-in-one-printer-series/5203208/document/c01935...
Link 2: HP Printers - Print Driver Settings Guide (Mac): https://support.hp.com/us-en/product/hp-envy-120-e-all-in-one-printer-series/5203208/document/c04701... Please check the duplex printing option under “Layout and formatting settings”
Hope this helps. Let me know how this goes. I genuinely hope the issue gets resolved without hassles and the unit works great.
To simply say thanks, please click the "Thumbs Up" button to give me a Kudos to appreciate my efforts to help. If this helps, please mark this as “Accepted Solution” as it will help several others with the same issue to get it resolved without hassles.
Take care now and have a superb week ahead. 🙂
DavidSMP
I am an HP Employee