import-module ActiveDirectory
$templateUser = get-ADUser user1
$targetUser = getADUser user2

$groups =get-adprincipalgroupmembership $templateUser
$groups2 = get-ADPrincipalGroupMembership $targetUser

foreach($group in $groups) {
    add-adGroupMember $group $targetUser
}

Add-ADGroupMember : insufficient access rights to performt the operation
At line:9 char:18
+ FullyQualifiedErrorID : Insufficient access rights to perform the operation,Microsoft.ActiveDirectory.Management.Commands.AddADGroupMember