I'd agree - it's a typical "tram tracks coin" - it's been flattened by a tram, train or simply (as echina speculated) smashed with a big heavy hammer.
There's really only one way a genuine "mint error" can come out larger than a normal coin: a broadstrike. A broadstrike happens when the collar die is missing, so the metal in the coin "squirts out the side" when it is compressed. Broadstrikes do not have milled edges, because the milling is applied by the collar die.
Your coin clearly has a milled edge. It therefore cannot be a broadstrike. And so, it cannot be a mint error.
There's really only one way a genuine "mint error" can come out larger than a normal coin: a broadstrike. A broadstrike happens when the collar die is missing, so the metal in the coin "squirts out the side" when it is compressed. Broadstrikes do not have milled edges, because the milling is applied by the collar die.
Your coin clearly has a milled edge. It therefore cannot be a broadstrike. And so, it cannot be a mint error.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis