You install a print queue to a SPM (Standard Port Monitor), WSD (Web Services for Devices), or USB (Universal Serial Bus) port.
After the print queue is installed, you install another queue to the same port.
After you install the second queue to the same port, you notice that BIDI (Bidirectional) communication is not working.
Having multiple print queues installed to the same port is not a supported scenario. In order for BIDI communication to work, the print queue can only enumerate one print driver.
To ensure Bidi communication works properly, do not install multiple print queues to the same port.