Let's start by defining the term "recast". A recast is a pan or pot made using another pan or pot as-- or as the basis of-- a pattern. If you think of a pattern as an original from which copies are made, a recast is a copy of a copy.
A recast is not necessarily the same thing as a counterfeit, which is produced with the intention to deceive.
The patterns used to make late 19th and 20th century hand-poured hollowware castings were more than simply representations of their final product. The side gating technique used in that era and after requires patterns to have all of the channels and risers through which molten metal would flow into the mold already attached as an integral part. Once the casting hardens and is released from the sand mold, the metal filling those channels and risers that hardened as well must be broken off. The roughness left at those break points is then ground somewhat smooth.
A recast, by contrast, is made by simply embedding an actual pan in a sand mold, cutting a hole or slit into the top of the mold, removing the pan after the sand hardened, reassembling the mold, then pouring the molten metal through the opening. Subsequently, the excess hardened metal at that single point-of-entry is broken off and the residual ground smooth enough to (hopefully) let the pan set level.
This quick and dirty method therefore leaves artifacts of the casting process inconsistent with the side gating technology used to cast the copied pan. After breaking off the excess hardened metal, a "sprue" or "gate mark" is left in the bottom of the casting. In the majority of cases seen, no attempt is made to conceal the original maker's markings.
This method was apparently used by many small, nameless foundries, in order to avoid the expense of actual pattern-making. Their goal was not to counterfeit name brand pans, but rather to simply create some usable wares for local sale.
A recast could also be the result of an individual, with the necessary resources available, creating a one-off or small number of copies. And, since aluminum is far easier to melt than iron, it might explain the prevalence of recasts of iron pans seen made with that other metal.
Common to most recasts, besides the atypical gating methods used, is their general sub-standard casting quality. Casting voids and other casting anomalies that would never have passed a genuine manufacturer's quality control are rampant.
Those not yet familiar with recasting may be fooled into believing they may have found a genuine pan, albeit one with unusual characteristics. Decades ago, even knowledgeable collectors for a short time believed a recast of an Erie skillet to be a newly discovered, genuine early example, and tried to fit it into the established Erie time line.
Conversely, there is no overarching reason to suspect a recast or counterfeit simply because a pan's markings are unfamiliar to you. Counterfeiters were largely opportunistic, mainly reproducing small, high value items like toys and tea-size cornstick pans. Recasts are typically just someone trying to make a usable piece, not a perfect replica.