modify script for duplicate renamed files - powershell

Question

Using the code below in PowerShell, I'm renaming many pictures. How do I modify the code to manage duplicates? Note; many of the photos have the SAME CreationTime value. As they occur, I need them to be output as:
yyyyMMdd-HHmm-1
yyyyMMdd-HHmm-2
yyyyMMdd-HHmm-3
etc.
Script:
Dir | Rename-Item -NewName {$_.CreationTime.toString("yyyyMMdd-HHmm") + ".jpg"}

Answer 1

Add more to your scriptblock to check paths and cycle through until it finds something unique:
Dir | Rename-Item -NewName {
$NewName=$_.CreationTime.toString("yyyyMMdd-HHmm") + ".jpg";
$i=1
While(Test-Path ".\$NewName"){
$NewName=$_.CreationTime.toString("yyyyMMdd-HHmm") + "-$i.jpg"
$i++
}
$NewName
}
Edit: Hm, I'm not sure why it would do that unless you didn't copy my code right. I ran it against a test folder and ended up with:
PS C:\temp\test> gci
Directory: C:\temp\test
Mode LastWriteTime Length Name
---- ------------- ------ ----
-a---- 10/12/2016 11:13 AM 35228885 20161012-1113.jpg
-a---- 10/12/2016 11:28 AM 31413221 20161012-1128.jpg
-a---- 10/12/2016 11:37 AM 33243498 20161012-1137.jpg
-a---- 10/12/2016 4:42 PM 2110424 20161012-1642-1.jpg
-a---- 10/12/2016 4:42 PM 3300892 20161012-1642-2.jpg
-a---- 10/12/2016 4:42 PM 3295345 20161012-1642-3.jpg
-a---- 10/12/2016 4:42 PM 101138881 20161012-1642.jpg
Edit2: Ok, fixed the issue where it can't manage more than 10 of a file with the same datetime.

Answer 2

try this, but modify the path C:\temp with your path directory
$listcouple=gci -File -Path "C:\temp" | select name, fullname, #{Name="Datstring";Expression={$_.CreationTime.toString("yyyyMMdd-HHmm") }} | group Datstring
foreach ($item in $listcouple)
{
if ($item.Count -gt 1)
{
$compteur=0
foreach ($value in $item.Group)
{
$compteur++
$newname= $value.Datstring + "-" + $compteur.ToString() + ".jpg"
Rename-Item -path $value.fullname -newname $newname
}
}
else
{
$newname= $item.Group[0].Datstring + ".jpg"
Rename-Item -path $item.Group[0].fullname -newname $newname
}
}