Posted by slang on October 4, 2008
A thinner, oversize “pancake” coin with rounded edges occurs when the collar does not contain the coin properly.

50 Cents, 1991, (KM.53), error, struck through another planchet outside the collar, resulting in an oversized coin, rev. almost blank, as struck.
Posted by slang on
If the coin is not ejected properly after being struck, a second impression is made on the same planchet. The second impression is frequently off centred as well.

10 Cents, 1982, (KM.3), error, double off-centre strike, obv. and rev., as struck
Posted by slang on
These occur when a planchet intended for a coin in one metal is inadvertently mixed with planchets of another metal. Off-metal coins are scarce .

5 Ringgit, Abdul Rahman, 1971, (KM.10), off metal error, struck on a 12-sided planchet, practically as struck.