If the company made the original booking on SWABIZ, the travel manager will have complete history of what transpired with the PNR.

Assuming the fares are identical, what you propose would be cost neutral to your girlfriend's company; HOWEVER, it could be considered misuse or inappropriate use of company funds and I would be very hesitant to do this absent approval of her immediate supervisor or travel manager. If she works for a company big enough to centrally handle travel bookings/have a travel manager, they probably have written travel policies and this could very well violate such policies.