[Kennindra47]

If a plane wreckage was found in the ocean with 300+ bodies and the plane was identified as Oceanic 815, you can bet your ass they would forensically test all of the bodies to confirm who had died in the crash and who, if anyone, was missing. Therefore, it is highly unlikely that 300 random bodies were used. I think Rocco's idea is probably closest. Unless the writers are going to overlook such a serious plot flaw, cloning seems like one of the only logical explanations. I also think Ben planted the plane but doubt he killed 300 people in order to do it.