Yeah.. I put one on top and one on bottom.. But I would STRONGLY urge you NOT to do that.. It is a SHI*** ride!! Way too stiff up front. I did it cause it was what I could afford at the different times. It was just to get me by.
If you want more, you would be WAY better off getting a 3" lift coil.. Way nicer ride. (which I will be doing soon to replace my spacers) You can get them new online for around $110+shipping.. This is probably where i'm gonna get mine when I have the funds. Not necessarily the best, but will be a heck of a lot better than what I have..
http://shop.suspensionmax.com/Shop/Control/Product/fp/vpid/5276192/vpcsid/7184730/SFV/32526
You can also just buy a set of used springs and pray they aren't sacked out. I just want to go new so I don't have to worry about it..