I have a system with 3 amd gpus and 1 nvidia gtx1070.
I used previous 6.x dualminers without a problem with bat file - the text provided:
EthDcrMiner64.exe -mode 1 -di 3 -r 1 -tstop 83 -epool pool_addr_hidden:8008 -ewal wallet_hidden/gtx1070 -epsw gtx1070 -dpool http://sia-eu1.nanopool.org:9980/miner/header?"address=sia_wallet_hidden&worker=gtx1070" -dcoin sia
"-di 3" - you enabled one nvidia card and skipped all amd cards. Remove this option to enable all cards.
That is exactly what I want. To enable only 1 nvidia card. It worked with 6.3 and older versions but doesn't work with 6.4