From your photograph, there looks like a LEFT and a RIGHT channel. And a space for an identifying label on each DB9 connector.

The COM# is dependent on the driver. Most of these cables allocate a COM# to each channel when first used with your PC. The driver will associate the unique identifier from the USB device. So you can swap physical USB ports and keep the COM#.

These cables are normally CDC class of device.

In my experience all of these cables will work with any programmers that make regular use of the RS232 e.g. send and receive ASCII strings. After all this is what RS232 as designed for.

Those programmers that bit-bang the RS232 control signals like DTR, RTS, CTS, DCD etc may not work.

Those "parallel port" programmers that bit-bang the control lines will probably never work with USB->LPT cables. But these particular cables tend to be as expensive as a new proper USB or RS232 programmer anyway.

David.