interrumping? What pervert made THAT typo? Geez you guys!
The cloning glitch in [[Generation I]] was discovered by accidental [[trade]]s, where dirty connectors or damaged link cables where responsible of one of the players to receive a cloned Pokémon. This was due to the lack of capacity of the link cables to send and receive the data at the same time, so in some cases
interrumping a trade resulted in cloning a Pokémon.
This glitch is very hazardous to the save file, because a trade needs to save the player's party in order to start the second part of the trade. But if performed wrong and the game has not finished saving, it will corrupt the saved data and force one of the players (or sometimes both) to start a new game.