I went to 'about this mac' and see here that it looks right. Is there an explanation for this?
That does not look right. There should only be ONE "Data" Volume.
Let me take a go at making it easier for you to understand. In the days before Apple changed things, a drive was "partitioned" into sections that could each be mounted into the operating system and accessed by the User (most of the time). Those mounted partitions looked like drives to the user, each one had a separate icon, different name, etc. Sometimes the multiple partitions were not available to the user and, as such, were "hidden" from the user. But when the right keys were pressed at boot time, the system would use those hidden partitions to boot into recovery so the user could restore the system, for example.
OK, Apple changed things in Sierra and on by changing how the hardware is formatted and used. Now, with what is called APFS (which is Apple File System) the hardware, instead of having partitions, is divided into "Containers" and inside the Containers are "Volumes" that are roughly the equivalent of what used to be partitions. If you look at your screenshots from Disk Utility, you see the hardware name is, "Aura Pro X2 Media." Indented under that name is "Container disk1" and under that is "Macintosh HD" and "Macintosh HD - Data 1" and "Macintosh HD - Data 2." What Apple did, starting with Catalina, I think, was to create two of these Volumes at the time the system was installed. On one, the "Macintosh HD" Volume, the installer put the system folders, what you can see as /System, /Library, and /Applications. On the Macintosh HD - Data" Volume the installer put /Users. But then, to keep the system looking like it used to, it merges the two volumes into one logical volume in Finder and on the Desktop so there you only see "Macintosh HD" and none of the details of the two Volumes it has merged. Disc Utility can see the separate volumes because it is the tool the User uses to add and delete volumes. Unlike previous partitions, in APFS all of the Volumes have access to all of the unused space in the Container, which is why you see the same 886GB Available on all three of the Volumes in your screenshot. As any of the volumes use that space, it disappears from all three "Available" numbers because it is shared. A bit like having multiple taps on a gallon bucket. All three taps theoretically have a gallon of liquid available to them, but as one opens to take some out, all three have less available.
So what I think happened with you is that in some installation or, more likely, re-installation, you pointed to the Volume named Macintosh HD as the install drive. That is how it would have worked in the old structure. However, by doing that in APFS, it did what it is programmed to do--put the system folders on the "Macintosh HD" volume and create a "Macintosh HD - Data" Volume. But because there was one there already, it added the "1" and "2" to keep the names separate.
Now, when the system boots, it makes the merged Volumes (Macintosh HD and Macintosh HD - Data) the "boot" drive logically, just as it would have done with a partition in the old scheme. And there are some things you cannot do to the boot drive, including deleting it. (After all, that's like trying to change the engine in your car as you are driving it--no can do.)
What you "SHOULD" see in Disk utility is more like what Rod showed--1 Macintosh Volume and 1 Macintosh HD - Data volume.
What Lifeisabeach suggested was to eliminate one of the "Data" volumes. That may be possible if the one you eliminate is NOT the one that the boot process has logically merged with the Macintosh HD Volume. It almost looks from your post #10 that both Volumes are mounted. Do you show disks on the Desktop? What shows there? If there is one named Macintosh HD and another with "Macintosh HD -- Data..." on the Desktop (Not in disk utility, on the Desktop), then the one on the desktop probably could be removed using Disk utility. Doing that will erase everything on that Volume, so make sure you have anything from it that you need before you try that.
As for installing BS, that won't fix it unless you do a full repartition of the hardware and let the installer create a new Container and in the Container a new Macintosh HD and Macintosh HD - Data, again erasing everything on the drive totally. If you just install over what you have, it will leave what you have. If you install and point to "Macintosh HD" as the install location you most likely will end up with "Macintosh HD - Data 3" as a new Volume. We had some poster here a few months ago with that situation. He, as I recall, did a clean install and partitioned the entire hardware again to get back to just the two Volumes.
Did that help any?
