question

Then I Scaffold Register, Login, LogOut, and RegisterConfirmation according to the tutorial. Here I select "Login", "Logout" etc., select ApplicationDbContext as Data Context Class and click add.

Can you tell how you did it? What are the settings of Data Context Class and User Class?

In my environment the builder.Services.AddDbContext... and builder.Services.AddDefaultIdentity... in the Program.cs generated by the Visual Studio 2022 are as follows:

 var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
    
 builder.Services.AddDbContext<ApplicationDbContext>(options =>
     options.UseSqlServer(connectionString));
    
 builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
     .AddEntityFrameworkStores<ApplicationDbContext>();

Are they the same in your environment? The duplications are also the same?

This is still an issue as of July 22, 2022. In fact, it has gotten worse.
When I attempt to Scaffold the Register page, as OP mentioned, it now creates an additional Data directory in the Areas->Identity directories.

It never did this in the past, especially considering I already have an ApplicationDbContext.cs and an existing Data directory in the standard structure of the solution... as generated by VS2022.

Simply deleting this directory also does not fix the issue, because it branches out to other errors that you must hunt down, which takes more time.

Having to track down these errors wastes time and creates frustration. This completely negates the basic principle of not wasting time while coding.

I am attaching snippets of BEFORE and AFTER the scaffolding to show what it was and what it creates.

Regards.