I got it to dual mine last night, I was stuck in the back and forth of sha256 / scrypt as well. Before using zadig to overwrite the driver my com port was 4 then it disappears as stated above. I changed the com port to 1 it the batch file for cpuminer and it fired up, very slowly mind you. Once it started hashing scrypt I launched cgminer and it went to work also. I did drop the clock speed for both. I am only using one miner mind you. Currently I am only getting 250 KH/s and 8.77 GH/s
I am sure this is of no/little help but that is what I did messing around and it worked.
I will give this a try also see what happens
Update: Both are detected using com1 for cpuminer, however cpuminer is not finding any shares at all
See below:
http://i1294.photobucket.com/albums/b609/louiemgallant/attemptatdualhashing_zpsd212051a.jpgSo still no further ahead for me
Have you tried lowering the frequency? 800 might be too much for dual mining. Also, make sure your power supply is supplying enough power. Back before cpuminer could disable the BTC cores my power supply was not powerful enough and the same thing happened, no found shares.
