What's The Most Errors You've Ever Seen On One Coin?

Mentioned it due to where I live there are numerous factories that produce nuts, bolts, screws and washers. Not to mention how far back this was but someone I used to know worked in one of them. This was in the days of pay phones. Where he worked they made wasers with no holes that matched Cents, Nickels, Dimes, Quarters. Mostly for pay phones but also for many other vending machines.
Many banks in this area have had their fill of rolls brought in by customers with similar blanks made in those factories. Most banks in this area now require people to leave all coinage for shipping out to a counting place and there is a charge for this.
Remember if you worked in a place that makes washers and you know what your doing, you could make a washer out of almost any material. And you could make them look almost like a coin.
Imagine too the people that make all those magician coins. Two headed, two tailed, cent/dime, quarter/nickel and many, many more.
One trip to a magicians shop makes me always wonder how many error coins are really real.