Jeyjey 100% possible to make backup HDD to HDD make sure na meron kang extra cables (IDE Cable or SATA) and pag luma pa ang hdd make sure the other one should set as Slave and the other should be MASTER(OS installed here)
bakit kaya nag hung na pag isalpak extra hdd,? try mung pag palitin yung mga cables niya, pag ganun parin, may sira na hdd mong extra, try mu na lang bili or hiram encloser niya, gawin mung external,,kung dimo siya maopen o mag hung pc pagkaopen, talagang may topak na hdd, try lang pare.