more than likely they the person who made the coin thought they had a limit of 42 but only set the transaction limit to 42 and the actual coin limit is higher. i can take a look in a second then edit this post
edit: i didnt have to look for more than 10 seconds... lol. on the github there was a merge commit on the 23rd of september (2015) where they actually set a hard limit to mining so that it fixes the max coin to 42.
https://github.com/fourtytwo42/42/commit/10247d029446163dfe3fa896b0747d5e21d8037chowever... since they are already well over 42 coins... there is no limit on the coins and the only way to fix this is to roll back the blockchain like 400,000 blocks.
so this coin is fucked on the only 42 coins principle.
tbh a lot of coin "devs" forget to put a limit on mining or staking so this will probably start to happen to a lot of poorly made clones in the future. i think 42 coin is just one of the first to actually hit the "max coin" number and have it fail