I have searched this site and many others looking for a way to "split" or mirror data from an USB device (bar code scanner) to two computers. We need to do a parallel cut-over from a legacy asset management system (whose interface, at each loading dock, is a LAN connected PC with an USB bar code scanner) to a Web application using a laptop with the same USB scanner.
Years ago I designed a RS-232 serial port Y cable that allowed the SMDR data from a PBX to go to both a data capture serial port on a computer and another device by utilizing signal diodes on each device transmit lead.The PBX transmit lead was split to each device's receive lead.
Not anticipating the firmware/software/timing and control logic involved, I thought all I needed to do was match a pair of diodes that would block the computers from sending or receiving data from each other, as I had done before. I've tried biasing the signal diodes with the T+ of each computer USB, to no avail. USB is much more technologically complex.
All the research I have read, so far, leads me to believe that I would have to design a "black box" which would interface between the scanner and the two computers. The box would look like a computer (host) to the scanner, a scanner to each computer, and thereby spoofing each component.
I hope that I’ll be able to find someone with a workable solution to this question.