Framing Errors & Simultaneous Connections

Device: Digi One SP
OS: Windows Server 2016
Realport: 40002549_H

My knowledge of serial is fairly weak so bear with me here.

Baud Rate: 1200
Data Bits: 8
Parity: None
Stop Bits: 1
Flow Control: None

on the Digi’s config page under Configuration > Serial Port > Advanced Serial Settings, I have “Allow multiple systems to simultaneously connect” checked and Control set to Shared

I currently have 2 VMs attempting to connect the Digi via Realport simultaneously.
There are redundant applications on the VMs both listening to the serial stream.
If either VM is restarted, the Digi experiences Framing Errors once the VM is back online.

I’ve narrowed down that it is not a problem with my listening application, it is only when a Realport connection is added.

Is there some simple setting I configured improperly? Does the Digi perhaps send a message along the stream when a new connection is added and if so can I disable that?

Any help would be much appreciated!