The reason you find SCSI is due to the history of this OS. Way back in Windows NT only SCSI drives were supported. A "software shim" was created to allow other drive types yet you will find this legacy detail to show and will confuse some that didn't know. That's not a cause for alarm.
As long as the BIOS does not show the drive, Windows shouldn't either.
Could this be related? 2nd drive no longer shows up in BIOS, my computer, or control panel system hardware. When I checked my C drive, in the control panel system hardware it's now listed as a SCSI hard drive, and includes a SCSI controller. How do I convert it back to a standard IDE SATA hard drive. And is this transformation is the cause of my lost 2nd drive?