I couldn’t find an easy quick way to do this so I took an old powershell script I found and modified it to work in Windows 2008 R2 and later environments.
1: import-module ActiveDirectory
2: cls
3: write-output "This script adds the destination user to all the Groups which the source user is memberof."
4: write-output " "
5: write-output " "
6: $SName = Read-Host "Please Enter the alias name of the source user "
7: $DName = Read-Host "Please Enter the alias name of the Destination user "
8:
9: $K = Get-ADUser -Identity $SName -Properties memberOf
10: foreach($group in $K.memberof)
11: {
12: Add-ADGroupMember -Identity $group -Member $DName
13: write-output $group
14: }
15:
Chris May 
Amazing script and works flawless. Is there a way to pull from a csv source and target and update?