Hi Zippy Zapp!
I always forget this configuration myself and awhile back took a photo and have it in my phone so whenever I need to know can pull it up. Which is all the time. Ha
The configuration I use is:
Right Drive as DF0:, Left Drive as DF1:
Middle Connector to DF1: and the end connector with the twist to DF0:
This configuration should eliminate both drive lights coming on when only accessing one drive.
If it doesn't then something might be wrong with the cable or double check and make sure the cable is correctly attached to the drive. I have a bad habit of inserting the cable only on the top pins and sometimes inserting the cable offset a row, where 2 end pins are not connected in the cable. So I always have to double and triple check my connections to make sure the cable is fully seated and inserted correctly.
Hope this helps some.
Robert
MyAmigaShop.com