Yes, Print2RDP is capable to print on both sides of the paper, if the given printer and printing application supports duplex printing.
In order to print no both sides of the paper, one must perform the following steps:
Connect to the server from the client computer.
Once connected, in the Printing Application, select the duplex printing in the printing application’s print window.
For example: In Microsoft Word > Print > Print on Both Sides
Click on the Print button to start the duplex printing to the selected printer.