A duplication caused by double replications. (A) A mitochondrial replication event (RP1) was initiated at OH1. (B) RP1 passed through OH2. (C) RP2 was initiated at OH2. (D) Both RP1 and RP2 terminated at OH1, while the nascent H-strand of RP1 was replaced by that of RP2. (E) The connection of the 3′ end of RP2 to the 5′ end of RP1, and the connection of the 5′ end of RP2 to the 3′ end of RP1. (F) The duplication was made permanent in the next round of replication.