Rocky install breaks Windows dual boot?

Starting with a working Windows 10 system, I tried to install Rocky 8.4 on a separate hard drive for dual boot. I let the installer use its default automatic partitioning scheme on the fresh hard drive, and it went fine. But it seems to have messed up the Windows boot loader. The boot menu now identifies the Windows drive as UEFI OS, whereas it used to say Windows Boot Manager. If I try to boot that one, I get this blue screen and it reboots.

I will try to repair it from the Windows installer. My question is, is it a known issue that the Rocky installer messes up other installed hard drives?

Yes, but you might not have checked (and written down) the exact device IDs that it decided to use.

Most dual boot setups (with two disks) are not really dual boot, there’s usually one disk with the “menu”.

You can have true dual boot, but in that case you’d need to use the menu in the “BIOS”.

True dual boot would allow you to unplug one of the disks and the other disk would still work.

I can tell the difference between the 2 disks because they are different sizes. I intend to use the BIOS boot menu to switch between the two, the “true dual boot” option as you call it. From linux, I can see the Windows NTFS partition is still okay.

When you did the RL install did you remove / disconnect the windows drive?

Can you post the output of lsblk

lsblk -o name,size,type,fstype,uuid,mountpoints