This is a result of atapicam being loaded, then an application attempting to use the scsi designators of 'cd'. Some optical drive applications require that the drives be scsi (or at least look they are).
cd0 and cd1 are the "scsi emulation" versions of acd0 and acd1
put a mountable disk in acd0, mount it, look at contents, unmount disk, mount cd0, look at contents
contents are the same (it's the same drive)
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