Odd behavior, Duo requests verification twice at every login

[Linuxmonger]

Our company has deployed an RD-Gateway and Remote desktop with Duo for 2 factor, and it works amazingly well for the users that have a Windows desktop to connect from.
In an effort to save a little cash, I am trying to set up users with a Raspberry Pi 4 and dual monitors, it also works amazingly well, they’re quick, cheap, easy to maintain and almost disposable.
The only issue we’ve had is that when users connect, they always get two requests from the Duo app to allow access, on Windows, they only get a single request.
The connection is using this command;

#!/bin/bash
User=${1} ;
Pass=${2}
# Uncomment only one of the two lines below.
LBI=“tsv://MS Terminal Services Plugin.1.Desktop”
# LBI=“tsv://MS Terminal Services Plugin.1.BuickQooks”
xfreerdp /cert-ignore /g:rd-gateway.here.com:4429 /gd:here /gu:{User} /gp:{Pass} /sound:sys:alsa /gdi:hw /multimon /f /u:HERE\{User} /p:{Pass} /load-balance-info:"${LBI}" /v:rd-gateway.here.com

If anyone has any idea what I’m doing wrong, I certainly appreciate a shove in the right direction!
Thank you!

[DuoKristina]

We’ve seen two pushes before from user connecting to RD Gateway with Mac clients (https://help.duo.com/s/article/1428).

In our troubleshooting we saw two connections pass through RD Gateway: one to the RD connection broker and one to the RD session host. The Windows RDP client was able to somehow use the successful authentication on the connection broker to skip authentication on the session host. The MacOS RDP client did not, so it authenticates twice. This would be silent without MFA, but with Duo installed the double authentication to RDG results in two Duo pushes or callbacks.

Possibly this explains what you experience from Linux clients as well.