I have a working Powershell Script that finds RDUsers , but I need to add an exception list to this code.

Here is a rundown of my environment.  We have a Business system program that runs primarily on RDS.  We have an RDS collection consisting of 7 servers.  The license to use this is expensive and the system would know if we go over.  So in order to not allow a user to log in twice (Keep in mind a GPO to log on once, won't work with 7 servers and the broker).  I created this script, and it works great.  "However"!!!  A monkey wrench came into this plan.  There are several users that DO need to log on with the same account twice.  So I need some kind of If function that if a certain user doubled up, its ok.  And not to Invoke-RDuserlogoff, like I have in the script.  I can create a CSV, or whatever, but I don't know how to add it to my script.  EXAMPLE.  User JANA, TMB, DLL, are exempt from this script logging them off.  Here is the code.  That is set to find anyone that is logged in twice.

Import-Module remotedesktop
$ClientUser =get-rdusersession | Group-Object -Property UserName |Where-Object {$_.Count -gt 1} | select -ExpandProperty name

$UserSessions = Get-RDUserSession -CollectionName TIMSV7 | Where-Object {$_.username -eq $ClientUser}

if ($UserSessions)
     {
     foreach ($UserSession in $UserSessions)
         {
         $UserSessionID = $UserSession.UnifiedSessionID
         $UserSessionHost = $UserSession.HostServer
           Invoke-RDUserLogoff -HostServer $UserSessionHost -UnifiedSessionID $UserSessionID -force
         }
}

So again this works.  Now how do I add somewhere in this not to log off users that I specify in variable, CSV, TXT?  Something.  I will be running this script every 15 minutes, and the users I want to exempt, wont change unless they leave the company.