I'm not understanding your "But," RTM. Please note that I have no stake in this other than in verifying who made it and/or sold it. OldToolNut thinking it resembles Plomb doesn't really mean anything more than Roy thinking the same thing, and I know Roy won't take offense to that. I'm not arguing with the rationale. I totally understand where both of them are coming from due to the profile of the pliers and the brand name on the handle being forged in such an intentional way as to have a dual purpose as a gripping surface, a concept Plomb used, explicitly calling it "Name-Nurl" in their catalogs as early as the mid-1930's.
But the facts seemingly defy it being a Plomb product. Unless everyone has missed it, there is no catalog or ad record of Plomb using "Push-Pull" as a brand name. If they did, and nobody has any record of it, it would have all kinds of other implications of epic proportions. So doubting that is not cavalier; jumping to that conclusion without documentation is. On top of that, their Name-Nurl pliers were made by Utica, which logically raises the possibility of Utica making pliers for someone else who copied the Plomb Name-Nurl grip idea. Also, let's keep in mind that Plomb did not apply the "Name-Nurl" handles exclusively to duckbills. Their dykes, linesman's, and battery pliers also had "Name-Nurl" grips in that era.
Maybe MR. X can tell us if the other "PULL-PUSHER" pliers he has seen before were duckbills or other kinds.
I hope that clarifies my position.