[rt-users] Placing 2 CF in RT ticket subject

[Nums]

I am trying to create a script which will pull 2 custom field values into the RT 
ticket subject upon creation. 
I am able to do it with one using script below, but 
unable to manage to pull 2 CF values, is this possible?

my $subject = $self->TicketObj->FirstCustomFieldValue('Custom Field Selection')

$self->TicketObj->SetSubject($subject);