It’s a good way for drivers to get disqualified and contractors to get terminated. They get a report every night and have to approve the stops with duplicate deliveries to the same address.
Express allows this practice during P1's if you also have P2's going to the same stop but they could possibly slow you down and cause you to have other late P1's. Let's say you have 1 P1 envelope but 20 computers to the same stop that are P2 and would take 15 min to unload them. It's permissible to come back later and deliver the 20 other boxes.