[Kazun]

Код:

$files = Get-ChildItem | Where {!$_.PsIsContainter -and $_.BaseName -match "\."}

$arr = foreach($i in $files)
{
	$files | Where {$_.Name -ne $i.Name} | Where {
		(Compare-Object $_.BaseName.Split(".") $i.BaseName.Split(".") -IncludeEqual -ExcludeDifferent).Count -eq 5
	}
}

$arr | Select -Uniq