MAVProxy multiple master connections


I was trying to forward a telemetry stream from flight controller (pixhawk cube black) with serial connections (TELEM1 <> RPi serial pins and TELEM2 <> USB Serial Bridge connected to same RPi) connected to a raspberry pi to a remote host over a network. Serial ports configured to use MAVLink2 at 115200 baud on the FC.

I am running mavproxy instance at the RPi by the following: --aircraft vehicle_1 --force-connected --master=/dev/ttyS0,115200 --master=/dev/serial/by-id/usb-Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0,115200 --out= --daemon

I am able to connect to the vehicle at the remote host ( --master= when both of the serial connections are present and also only one of them is connected to the flight controller. So I am able to create a redundant connection between RPi and flight controller.

If there is only one serial connection to the RPi (TELEM1 or TELEM2), I got 0 packet loss. But when both of the serial connections are present, I got huge packet loss (more than healthy received packets). At the main wiki page it says:

Multiple --master can be used. MAVProxy will sort the packets into a single stream automatically. This is useful if independent redundant links are being used.

I can see these packet losses on both mavproxy console and Mission Planner debug screen (and also link status). MAVProxy version is 1.8.40 on computers.

Is there a way to prevent this or some configuration in mavproxy?
I only wanted to do this to create a redundant serial connection between the onboard flight computer and the flight controller.

Thanks for your help.