start in one cmd or shell ethminer with propper parameters and on a second sgminer-decred with -I 18 and below ... will let you mine decred and et* at same time and hashrate on ethminer will not drop down ... you could play with the -I parameter... raise em or lower em and take a look at hashrate on ethminer... if it drops go 1 step back
Interesting, I tried this before when I first starting mining and it killed my eth hash rate, but will take another look again since I was on the correct track and have learnt a lot since I started.
Thanks for the response, it's appreciated.