param
(
   $url = $(Read-Host -Prompt "SiteCollection Url")
)

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue

$Logfile = "duplicates_log.txt"

Function LogWrite
{
  Param ([string]$logstring)
  Add-content $Logfile -value $logstring
}

function tryDeleteNode
{
   param($node,$dictionary,$nodeCollection)

   $title = $node.Title

    if(!$dictionary.ContainsKey($title))
    {
        $dictionary.Add($node.Title,$node.Url)
    }

    else
    {
        if($dictionary[$title] -eq $node.Url)
        {
            if($node.Children.Count -eq 0)
            {
                echo "       -> Deleting Duplicate Node: $title" 
                $nodeCollection.Delete($node)
                $global:didDelete= $true
                $temp = (get-date).ToString() +";"+ ($site.Url) +";"+ ($title)
                echo "$temp"

                LogWrite $($temp)
            }
            else
            {
                echo "       -> Dupe Node $title has children, Skipping..."
            }

        }  
        else
        {
            echo "       -> Duplicate title $title found, but mismatched link, Skipping..."
        }

    }

}

function deleteNodesRecurse
{
   $nodes = @{}
   foreach($node in $quickLaunch)
   {
       $childNodes = @{}

       foreach($child in $node.Children)
       {
           tryDeleteNode -node $child -dictionary $childNodes -nodeCollection $node.Children
       }

       tryDeleteNode -node $node -dictionary $nodes -nodeCollection $quickLaunch
   }

}

function deleteGlobalNodesRecurse
{

   $nodes = @{}
   foreach($node in $gnavNodes)
   {

       $childNodes = @{}
       foreach($child in $node.Children)
       {
           tryDeleteNode -node $child -dictionary $childNodes -nodeCollection $node.Children
       }

       tryDeleteNode -node $node -dictionary $nodes -nodeCollection $gnavNodes
   }

}

$sitecoll = Get-SPSite $url

write-host "SiteCollection: " $sitecoll.URL 

foreach ($site in $sitecoll.AllWebs) 
{ 

    write-host " -> Site: " $site.URL 

    do
    {

        $quickLaunch = $site.Navigation.QuickLaunch

        $global:didDelete = $false

        deleteNodesRecurse

        $pub= [Microsoft.SharePoint.Publishing.PublishingWeb]::GetPublishingWeb($site)

        $gnavNodes = $pub.Navigation.GlobalNavigationNodes;

        deleteGlobalNodesRecurse

    }

    while($global:didDelete)

    $site.Dispose()

}

$sitecoll.Dispose()