Two Volumes Named "Macintosh HD - Data" Now Appear in Disk Utility in Addition to "Macintosh HD".

Must be a bug that is creating it then at some point in your workflow - maybe its a certain app you're installing that triggers it. and if it contains nothing I would just delete it.

if you do Shift + Command + period (reveals hidden files) does it show anything that looks important?

This looks to be different. The doubled drives that I initially had, and then resolved were named "Macintosh HD Data". Its weird that you have 2 Macintosh HD drives. Catalina should have 1 Macintosh HD drive and 1 Macintosh HD Data drive. Do you not have a drive that was marked Data?

Same exact thing as @haudt89 I have been trouble shooting the fan constantly running and that's how I came across this. I'm not sure it's related either but that's how I found that I had two drives showing.

I read somewhere else that every time you reinstall Catalina it adds another Macintosh HD Data.

Hello! I have this question too. But I can not delete Macintosh HD. Could you please help me?

Thank you so much!

To follow up: I have an iMac and a MBP. I did a clean install on both systems — and both exhibit the behavior described above (two HD - Data volumes).

I followed @Brallen01's tip and got... nothing (see screenshot); no vol identified (note also: Forklift does NOT show the rogue second data volume).

For completeness, the third-party apps I installed are:

A Better Finder Rename

Bartender

Default Folder X

Dropzone

Little Snitch

LaunchBar

Lyn

Marked2

Microsoft Office 365

Omnigraffle

Printopia

Scrivener

Studiometry

Typinator

As I did on my iMac — I'm going to delete the second volume, and see what happens :)

I had the same issue as well. I saw this after going back to Mojave (via TM) to update some iPhoto-to-Photos files. I rebooted via option-command-R (Restore), and used TM to go back to Catalina. I found this (via Disk Utility)...

Seeing this as an error I then did a restore using the same option-command-R, but asking for Catalina. Now, I have 2 Data drives. I took snapshots of all 3. Note that I somehow have 6 volumes!

Can someone help?!?

Were you able to actually delete it or just unmount it? How did you go about deleting it? I unmounted it and Time Machine started working, but I’d prefer to delete it entirely. I also got a message about how I was backing up from an encrypted disc to an unencrypted. I thought this was odd since I didn’t turn on the encryption option when I first set up my computer.

Same thing happened to me, no answers yet.

When you say you "reinstalled your apps" how did you do this? from a back-up, re-downloaded them from the app-store, downloaded them off the internet?

thanks.

Modify of apps from App Store. Some directly from developer sites, trusted apps such as Default Folder X, Forklift, and similar that are essential to my workflow. Also Office 365.

Same here, asked to rename Macintosh HD - Data because it had an alias of my Time machine external drive in it and would not back up. now have three Data disks

Sorry I meant two Data disks

Just the ordinary invisible files:

Def a bug...

which one of the 2 volumes i have to unmount to make the time machine working again? thanks