Get Duplicates from PowerShell Datatable using LINQ

Get-Duplicates.ps1

# Create Datatable
$dt = New-Object System.Data.Datatable "Music"
[void]$dt.Columns.Add("Artist")
[void]$dt.Columns.Add("Genre")
[void]$dt.Columns.Add("Album")
[void]$dt.Columns.Add("ReleaseYear")

# Add data
[void]$dt.Rows.Add("Poison","Glam Metal","Open Up and Say... Ahh!",1988)
[void]$dt.Rows.Add("Cinderella","Night Songs","Flesh & Blood",1986)
[void]$dt.Rows.Add("Eazy-E","Gangsta Rap","Eazy-Duz-It",1988)
[void]$dt.Rows.Add("Tim Smooth","Southern Rap","I Gotsta' Have It",1991)

# Add dupes
[void]$dt.Rows.Add("Poison","Glam Metal","Open Up and Say... Ahh!",1988)
[void]$dt.Rows.Add("Eazy-E","Gangsta Rap","Eazy-Duz-It",1988)
[void]$dt.Rows.Add("Eazy-E","Gangsta Rap","Eazy-Duz-It",1988)

# Perform the dupe check
[void][Reflection.Assembly]::LoadWithPartialName("System.Data.DataSetExtensions")
[void][Reflection.Assembly]::LoadWithPartialName("System.Data.Linq")

# Add a count column prior to making the dataset a LINQ list.
[void]$dt.Columns.Add("DupeCount")

$list = [System.Data.DataTableExtensions]::AsEnumerable($dt)
# Actually don't need! -> $list = [System.Linq.Enumerable]::ToList($enum)

# Group By
$groupbyquery = [System.Func[System.Data.DataRow, string]]  { param($row) $row.Artist, $row.Album }
$groupby = [System.Linq.Enumerable]::GroupBy($list,$groupbyquery)

# Where, can probably use Any, too.
$wherequery = [System.Func[System.Object, bool]] { param($row) $row.Artist.count -gt 1 -and $row.Album -gt 1  }
$where = [System.Linq.Enumerable]::Where($groupby,$wherequery)

# Select distinct, and add a count
$selectquery = 	[system.func[System.Object,System.Object]]  { param($row) 
	$null = $row.Item(0)["DupeCount"] = $row.count
	$row.Item(0)
}
$select = [System.Linq.Enumerable]::Select($where,$selectquery)

# You could streamline it, too.
# [System.Linq.Enumerable]::Select([System.Linq.Enumerable]::GroupBy($list,$groupbyquery).Where({$wherequery}),$selectquery) 

# Build & populate new dupetable
$dupetable = $dt.Clone()
foreach ($row in $select) { $dupetable.ImportRow($row) }

# Remove count column from original datatable
[void]$dt.Columns.Remove("DupeCount")

# Show your results. Orderby can probably be performed above, but whatever.
$dupetable | Select Artist, Album, Dupecount | Sort-Object Dupecount