Get memory used by every user in Windows server using PowerShell

Question

I want to generate a report on the disconnected users on the servers with the memory allocated to them. I am using the below script.

Get-WmiObject Win32_Process |
    select @{N='User';E={$_.GetOwner().User}}, WorkingSetSize  |
    group user |
    select Name, @{N='CPU';E={($_.Group.WorkingSetSize |
        Measure-Object -Sum).Sum / 1Mb
    }}

However, the above script generates a different value (Almost double the value of MB consumed than what is shown in the task manager) than what is shown in Task Manager and also it doesn't show the disconnected users.