Progress records suggest that the Phils were no more efficient than the singular version. Though Left Phil (Phil's left, the right side to anyone facing them) carried a more serious demeanor than Right Phil, who if anything was more scatterbrained and silly than ever, neither could be considered even a passable employee by any reasonable standards.
Ignefe, the Phils' secretary, is thought to be the only reason the new doubled workload hoisted upon the Phils got carried out at all. Additionally, the Phils tended to disagree on nearly every issue the two were faced with together. At the end of their first day together, the two disagreed on whether to take the tram back to the dorms or to grab a snack at the cafeteria. The dispute lasted 14 hours and was only settled when they heard the morning announcements and sat back down at their desk.
After this problem persisted through the infamous weekend, other employees began delivering the Phils meals to their desk and they did not leave the office at all until long after the end of the war. As a result of the argumentative confinement, the drop box Phil was intended to use for messages as a spy went empty. Helminth House received word that Phil had been cut in half and took his further silence to mean he was dead, either by accident or by counter-espionage. Nobody at Helminth particularly cared and the short lived spy program atrophied away as the factories and world at large turned their eyes to global warfare.