Identifying Windows 10 \Device\Harddisk1\DR2

How can I tell which physical device this actually is?

You can use wmic diskdrive get caption, deviceid, size to match up the devices shown with physical disks.

Example output from my laptop:

DISKPART> list disk

  Disk ###  Status         Size     Free     Dyn  Gpt
  --------  -------------  -------  -------  ---  ---
  Disk 0    Online          465 GB      0 B
  Disk 1    Online           59 GB      0 B
  Disk 2    Online         2794 GB  7168 KB

And:

F:\test>wmic diskdrive get caption, deviceid, size
Caption                            DeviceID            Size
WDC WD5000LPVX-08V0TT5             \\.\PHYSICALDRIVE0  500105249280
SanDisk Cruzer USB Device          \\.\PHYSICALDRIVE1  64009128960
Seagate Expansion Desk USB Device  \\.\PHYSICALDRIVE2  3000582144000

As you can see from the deviceid, and confirmed by the sizes, the devices are listed in the same order on my Laptop.

Note:

• The OP has stated that the wmic on his PC lists the devices in the reverse order. The information still allows the disks to be identified.