At the moment, there isn't a way to set up double printing order tickets with Square for Restaurants. However, here's a great a workaround that should help!
If you want to send two identical order tickets to a single printer, you can create two printer stations for one physcial printer.
1. Open the Square for Restaurants app.
2. Tap Account > Setup Hardware.
3. Make sure your compatible printer is plugged in and ready. Tap Create a Printer Station.
4. Enter the printer stations details and make sure to select the applicable printer > Save.
5. Now, create another printer station, but select the same physical printer.
Now when you print an order ticket, your kitchen will receive duplicate tickets for each order. Note: The above workaround won't work if you're using 2-ply paper.