How is your CPU load? Usually each GPU gets its own worker thread that is capsuled of the others.

As for the .bat problem: did you write in a password? When --pass is send to lolMiner the next element is treated as password. If you do "set "PASS=" this kind of kills the --device parameter.

What you can do is figuring out ideal commandline to run the miner without the .bat and then copy over the whole string to bat... that will also work