I've also received checks several times. I've never cashed them, though; I have no idea what the correction was for, and the little paranoid, anti-authoritarian, legally illiterate conspiracy theorist sitting on my shoulder tells me a few bucks isn't worth the risk of falling for the IRS's clever entrapment scheme--because cashing a check can
in theory constitute affirmation of the correction, which could have been erroneous for all know, and thus with some handwaving constitute fraudulent affirmation.
In reality the Federal IRS is a paper tiger compared to the California Franchise Tax Board. The FTB will shoot and ask questions later, and that's more than figurative if not quite literal. The FTB once garnished a paycheck while I was in the middle of correspondence with them.
From first person anecdotes I've heard, some other state tax authorities are similarly ruthless. My father got screwed out of a significant sum (in working-class terms) when Alabama came after him on the basis of some fraudulent 1099s (inflated payment amounts) from when he was a construction contractor. He had already moved to another state and it had been many years since the fraudulently reported income, making it infeasible to fight as it would cost too much to collect enough evidence to rebut Alabama's claim. While the Cal FTB has made national headlines a few times, most state services never make national headlines, so everybody just assumes the IRS are the bad guys, when in reality I think the IRS are relative softies.