So, what's the problem then? As Paul said, Format the 2nd HD in disk management, and assign a drive letter to it. If your BIOS and Computer Management both see the drive, then formatting is all that is needed.
they both boot depending where i install them in laptop.one boot win 7 and the other boot debian. ie:i cant see the one with debian on it when i boot with windows
Likely because of the filesystem that's on Debian. Windows may not be able to see your data.