What is wrong with AMD GPU at Dual Mining ?
My Dual Mining Settings:
EthDcrMiner64.exe -epool eth-eu1.nanopool.org:9999 -ewal MyAdress -epsw x -dcoin sia -dpool stratum+tcp://sia-eu1.nanopool.org:7777 -dwal MyAdress -dpsw x -ftime 10
Try to play with -dcri key. Set it about -dcri 10 and press + / - in miner window to find the best value