@iamjim For each partition/volume within a disk, Windows assign a unique Volume GUID as a mount point.
Open Admin command prompt and type: mountvol You'll get a list of mount points for each partition/volume and the letter assigned to each. All drive letters have been locked with Windows "forgetting" to release the drive letters when drives are removed. Check whether automount is disabled and enable it if it is disabled.
The assign command was introduced with MS-DOS 2.0 and has been available up to 6.0 where it was removed because of a concern with data issues.
It was later made available on the MS-DOS 6.0, 6.2, and 6.22 supplemental disks.
What causes signature collision is when you clone one disk to another in which case the disk signature also cloned to the other disk then Windows will put the cloned disk Offline.
Each disk has a unique disk ID and Windows does not mess with it except checking to make sure its signature is unique with other disk(s).Reboot the PC and let Windows re-assign new mount points for each volume/partittion. Then automount enable [ENTER] "automatic mounting of new volumes enabled" Close Command Window. Download v 0.8.1 of the from https:// down on this page till you see Drive Cleanup V 1.5 ) (Note: You can use the latest version V1.5.0 too.If still does not work: Back up your data from the troubled disk, use diskpart to re-initialize it. I have been using v 0.8.1 since long regularly) Unzip it to a folder, say drivecleanup.I have two SATA hot-swap drives that I alternate between each day for backups.When using Windows 7 I was able to assign the disks to g: and then after the initial assignment, windows would remember this and assign it to g: on each subsequent use. How to Change and Assign Drive Letter in Windows 10 By default, Windows 10 will automatically assign an available drive letter to any connected internal and external storage devices.You might prefer to right click the name of a partition in the upper pane, and then if Change Drive letter... Again, please confirm where you are clicking on Drive Management. It hides more than what it reveals and also misleading .Please post a full screen screenshot of Windows Disk Management . Move the vertical as well as horizontal seperators appropriately so that all information can be seen. Follow the guidelines here Disk Management - How to Post a Screenshot of | Windows 10 Tutorials That should help people here help you better.This has nothing to do with the problem he/she has.Obviously, both disks are Online so there is no disk signature collision.Where a drive has partitions, you assign a drive letter to a partition, not a drive.It looks as though you've rt clicked on the drive, not a partition.