Heteroplasmy occurs when 2 different dna sequences are found in nuclear dna as a result of the occurrence of a random mutation.

I think this is false; Heteroplasmy is the presence of more than one type of organellar genome within a cell or individual. It is an important factor considering the severity of mitochondrial diseases. Because most eukaryotic cells contain many hundreds of mitochondria with hundreds of copies of mitochondrial DNA.