Accidentally installed macOS Big Sur in Macintosh HD - Data

amyfq wrote:

Can you verify that you have no user data installed on this macOS....(?)

From what I see the the Macintosh HD disk1s7 and corresponding SnapShot both 15.1 GB mis-labeled as "Macintosh HD - Data"

Therefore the disk1s5 mislabeled as "Macintosh HD" which is your User files is only showing 852.0 KB (basically nothing)

The 15.0GB disk1s1 is the ghost mis-labeled as "Macintosh HD -Data"

If that is the case I would simply start over: erase/reformat/initialize the Parent Drive and reinstall the macOS a new, then restore your user data from backup.

How to erase a disk for Mac - https://support.apple.com/en-us/HT208496

How to reinstall macOS from macOS Recovery - https://support.apple.com/en-us/HT204904

amyfq wrote:

I've accidentally installed in macOS Big Sur in Macintosh HD - Data in MacBook Pro 2015. Will there be a problem? Thanks!

Hmmm... for a look see.. Hard to believe it installed in some unorthodox way.

Applications/Utilities/Terminal.app

Lets see the output from your the command line using the Terminal.app, copy and paste:

diskutil list internal

you can copy and paste the output here.

I've been wondering if there is a problem. Here is what I would expect when you install on - Data.

All of the Data folders that were located at the root level of the drive should be moved to somewhere in /Users/Shared/Relocated Items/

I don't know if it will actually see it as an old-style single-volume OS and split your data over to the new - Data volume which will be named with - Data - Data.

You may be ok, or you may have to recover all of your data from Relocated Items.

You will end up with an orphaned Macintosh HD volume (unless you deleted that, first). You should be able to remove it in Disk Utility. It would be mounted at /Volumes. You can see the Mount Point in the info pane when you select that volume in the list.