PowerShell ISE: Move duplicated files to another directory

Question

I have to move older duplicated files into another directory while keeping the latest copy of each original filename. I need to keep them for a week in that location and then delete them. I have the delete-item already working just need some guidance on the moving the older duplicates.

Example

C:\Temp
text1.txt.           14:03 PM
text2.txt.           14:03 PM
txt1.csv             14:04 PM

C:Temp\Source
text1.txt.           14:01 PM
text2.txt.           14:04 PM
txt1.csv             14:06 PM

The goal is to have the written the older files into the D:\ for example while keeping the structure the same to avoid an overwritten error in the future with other files

D:\Temp
txt1.csv             14:04 PM
text2.txt.           14:03 PM

D:\Temp\SourceDropped
text1.txt.           14:01 PM

Result Outcome and have the C:\ now like these for example

C:\Temp
text1.csv             14:03 PM

C:Temp\Source
text2.txt.           14:04 PM
txt1.csv             14:06 PM

I have tried this but the Move-Item is not moving them

 $dirC = 'C\Temp'
 $dirD = 'D:\Temp'

 Get-ChildItem -Path $dirC -Recurse -File |
 Select-Object -Property FullName, Name, LastWriteTime|
 Group-Object -Property LastWriteTime | 
 Where-Object -Property Count -GT 1 |
 ForEach-Object {
 $_.Group |
 Sort-Object -Property LastWriteTime -Descending |
 Select-Object -Skip 1 |
 Move-Item $_.FullName $dirD -Force #-WhatIf
 }

Also tried hashing them but it does not follow the structure when copied over

 $dirC = 'C\Temp'
 $dirD = 'D:\Temp'
 $hash = @{}
 Get-ChildItem -Path $dirC -Recurse -File | ForEach-Object {
 $filepath = $_.FullName
 $filehash = Get-FileHash -Path $filepath  -Algorithm SHA256 |
 Select-Object -ExpandProperty Hash

 if($hash.ContainsKey($filehash)){
  Move-Item -Path $filepath -Destination $dirD -Force
 }
 }

Answer 1

This might help you get going, essentially, first groups files by their .Length to avoid overhead of hashing them without need. Then, if the groups have more than 1 file, it will group them by MD5 hash and, only if the files have the same hash it will sort by .LastWriteTime and skip the newest one, the rest should be moved to $dirD.

-WhatIf should be removed once you have confirmed the code is doing what you need.

Get-ChildItem $dirC -File -Recurse | Group-Object Length | ForEach-Object {
    if ($_.Count -eq 1) {
        # nothing to do with a single file, no filehash needed
        return
    }

    # if the group has more than 1 file, get their hash
    $groupByHash = $_.Group | Group-Object { ($_ | Get-FileHash -Algorithm MD5).Hash }

    foreach ($group in $groupByHash) {
        if ($group.Count -eq 1) {
            # nothing to do with a single file, skip
            continue
        }

        # sort by LastWriteTime and skip the last file (the newest)
        $group.Group | Sort-Object LastWriteTime | Select-Object -SkipLast 1
    }
} | Move-Item -Destination $dirD -WhatIf