a couple of years ago, I found Nilda's technique for double embossing, I emailed her and asked her permission to write up her instructiions, she gladly gave me permission. (uses cuttlebug)
It turns out very nice, and you could put a stamp in the middle. I have them in pdf form and I will glady share the technique
if you want to email me at firstname.lastname@example.org
with double embossing in the subject line.
here is her site
the cuttlebug spot: Double embossing with Cuttlebug and nestabilities