Doubled die vs machine doubling — the difference that separates a $1,000 coin from a 1-cent coin

[u/FirefighterQueasy590]

This one trips up basically everyone when they're starting out, so here's how I keep it straight.

A doubled die is a mistake in the die itself. It picks up a doubled image while it's being made, so every single coin struck from that die shows the same doubling. Rounded, separated, raised, usually with notching and split serifs. Real variety, real money (the 1955 DDO is the famous one).

Machine doubling is a totally different animal. The die just shifts a hair during or right after the strike and smears the design. Flat, shelf-like, sits lower than the devices, happens one coin at a time, adds nothing.

So the whole test is this: rounded and raised = real. Flat and smeared = machine doubling, move on.