How do you separate two hard drives that look like their sharing most of the same stuff?
I'd love to help you with this, but I'm a bit confused on what
you mean.
Do you mean that you have two, separate physical harddrives with
identical data? If so, did you copy it yourself, or use something
like RAID1?
Or do you mean ONE hard drive with two partitions? If this is
the case you can reformat the drive- however this erases the
partition you reformat. To 'combine' them together as one drive you
must reformat BOTH- wiping the entire harddrive. (This only applies
in Windows, and some Linux OSs. In Apple Macintosh, you can just go
to Disk Utility and resize them on the fly without even
rebooting.)