good clone programs will show the serial number of the hard drive that way you are doubly sure.
i get a little paranoid too when i have only 1 existing drive of a machine and i need to re-clone it.
ive used hdclone by miray soft
http://www.miray.de/home/index.html it's pretty good even for the free version.
I also have a stand alone 1-4 hard drive clone machine...it's slow as hell but works 100% of the time. Plug the original to the mater and a blank to one of the 4 interfaces and in a few hours it's done.