If I want to attach second hard disk with the same configuration of master hard disk, then system doesn't show second hard disk altogether or new hard disk begin to malfunction. Such as suddenly begin to give sounds like TICK, TICK TICK. Suddenly vanishes from the 'MY COMPUTER' drives. Suddenly denies to copy paste functions.
Run the Seagate Diagnostic/Repair software off a floppy, can download it from the the Seagate sight assuming both drives are Seagates, other wise get the software from the mfg web site. Try a different SATA connector. Are both drives recognized in the BIOS and Windows?