Getting only a repeating files from directory and subdirectories - powershell

Question

I'm trying to do script for finding non-unique files.
The script should take one .csv file with data: name of files, LastWriteTime and Length. Then I try to make another .csv based on that one, which will contain only those objects whose combination of Name+Length+LastWriteTime is NON-unique.
I tried following script which uses $csvfile containing files list:
$csvdata = Import-Csv -Path $csvfile -Delimiter '|'
$csvdata |
Group-Object -Property Name, LastWriteTime, Length |
Where-Object -FilterScript { $_.Count -gt 1 } |
Select-Object -ExpandProperty Group -Unique |
Export-Csv $csvfile2 -Delimiter '|' -NoTypeInformation -Encoding Unicode
$csvfile was created by:
{
Get-ChildItem -Path $mainFolderPath -Recurse -File |
Sort-Object $sortMode |
Select-Object Name, LastWriteTime, Length, Directory |
Export-Csv $csvfile -Delimiter '|' -NoTypeInformation -Encoding Unicode
}
(Get-Content $csvfile) |
ForEach-Object { $_ -replace '"' } |
Out-File $csvfile -Encoding Unicode
But somehow in another $csvfile2 there is only the one (first) non-unique record. Does anyone have an idea how to improve it so it can list all non-unique records?

Answer 1

You need to use -Property * -Unique to get a list of unique objects. However, you cannot use -Property and -ExpandProperty at the same time here, because you want the latter parameter to apply to the input objects ($_) and the former parameter to apply to an already expanded property of those input objects ($_.Group).
Expand the property Group first, then select the unique objects:
... |
Select-Object -ExpandProperty Group |
Select-Object -Property * -Unique |
...