External Time Machine SSD shows up two times

Does Apple actually answer questions here, giving support?

Otherwise, I can only find "Give Feedback" which does not really help with actual problems.

On topic:

I use an Samsung T5 as Time Machine device.

Orginally, I added it directly to the USB-C port of my Mac Mini M1 with latest Big Sur.

Then, I added a Thunderbolt Dock and connected the device to this.

When I now enter Time Machine Preferences and then "Select Disk", I see the same device two times:

The first entry is used, as it offer "Remove Disk" as option.

The second entry is "available" and offers the "Use Disk" option ... it strangely displays "Case Sensitive"...

I have no idea what that Time Capsule is about.

Anyways, why is the disk listed two times?

Why does one show "Case Sensitive"?

And how get I get rid of the second entry?

Many thanks :-)