I can only speculate, but speculate I will. My scenario is that the coin was struck or cast in Africa. Decades ago, a collector, visiting Ethiopia told me how he'd fond a pair of dies for making a MT thaler in a market stall. He wanted to buy, but the stall holder didn't want to sell to a foreigner and moved the mould out of view. He talked to the locals, who said that the object of the exercise was not to deceive but to replenish the dwindling supplies of MT thalers. They also said that demand had tapered off to the point where it was restricted to the most "conservative" farmers. These stories should of course be taken with a grain of salt, because the locas wouldn't want to have the attention of the authorities over illegal practices acting on information from a blabbering foreigner.
Struck or cast? Do the
"ping" test and find out. You must have plenty of genuine coins for comparison. Cast coins tend to be slightly larger, but the edge may have bee filled off to hade the seem between the two halves. My African forger could do either with the right material and some practice. The funny edge is because that's the do-it-yourself part. British forgers
can't get it right either.
Muling is the hallmark of the sloppy forger.
Not having handled the coin, my favorite would be that it's (weakly) struck. The dies didn't match and one die may have been "enhanced" on points where it showed much corrosion.
Peter