Hard-disk, master versus slave

I added a 2nd h-disk so I could copy image of 1st drive on to it (to subsequently install drive into another PC to save having to rebuild Win95+apps over again). But I forgot to set 2nd drive as slave! – image copy worked OK, but I could not reboot PC until I had removed both the 2nd h-disk AND the CD-ROM..!? I suspect the cause is due to having 2 master h-disks present at same time, and the BIOS is now confused … but how do I reverse the ‘damage’..?? Can anyone help? Thanks