A double corruption allows the player to obtain the modified Pokémon in an Egg without hatching it. To cause a double corruption, the player should perform the usual steps to obtain a regular Egg, but leave the Egg in the storage system and corrupt it again. The Egg must not be picked up, or it will never corrupt into the desired unhatched Pokémon (unless the Pokémon is specifically crafted to work around this; e.g. a "Dots" Egg that had Flash as the fourth move).
Double corruption allows the player to obtain the Pokémon without going through hatching, which preserves the Held Item, EVs, Origin, Obedience, Ribbons, Experience, Contest Stats, PP Boosts, etc. While a simple corruption slightly changes some of the Pokémon's values (Move 2 and Move 4 will always be Glitch Moves, for example), a double corruption
The Eon Ticket, AuroraTicket, and MysticTicket, if held by a storage box Pokémon, cannot be taken and used to travel to an event island, as the flag must also be set. However, Glitzer Popping may rarely activate an NPC on the second floor of a Pokémon Center who will give an Eon Ticket while activating the flag. Additionally a derivative of Glitzer Popping known as the Pokémon news reporter glitch can be used to set the flags, by sending the 104th Pokémon into battle, checking that it has specific attributes (which will be random) and letting its HP drop to a specific value.