OK, I have managed to get it working...
First, I re-downloaded the dual boot installer and extracted the files. Then I uninstalled the rockbox drivers from the pc.
I put the dingoo into boot mode and was prompted by the hardware wizard, and I re-installed the rockbox drivers.
I disconnected the dingoo from the pc, reset it, then put it back into boot mode with B/reset, connected it back to the pc and ran the two command lines which then ran fully as per the guide (they didn't before).
However, Dingux didn't run and I only had a black screen, this is the problem that I also had with my first dingoo. I tried the above process a couple of more times without success.
I remembered reading in the FAQ about putting the dingoo into boot mode with B/power off as opposed to using the reset button, and then running the command lines, so I re did the process above including this alternate step, and this time it worked without any error.
I hope this information helps others who may be having similar problems, and thanks to everyone who offered me their advice.