what exactly is double drip coffee?
I think the warning in the last post is probably correct. I can't help but wonder why you are asking; is it because you want your drip coffee to be stronger?
If so, my guess is that you'll want to use more ground per cup of water. See the link to instruction from the Coffee Review below.
I have no idea what double drip coffee is, but I suspect it involves one of those cone type things that actually makes drip coffee. You cannot run coffee through a coffee maker twice. Firstly because it won't work with hot liquid - that's why you use cold water - and secondly because you shouldn't put anything but water in the reservoir because it will get into the heating element and go rancid or something equally evil and ruin your coffee maker and probably make you sick before you realize what that funny taste is. Not that I know this from experience or anything - I would never do anything like that. But a slightly dimwitted prep cook might...and he might have to pay for the coffee maker out of his next paycheque. *Sigh* Good help is so hard to find.