I believe this is done to ensure accuracy. DNA paternity testing involves the use of DNA profiling to determine whether two individuals are biologically parent and a child. The test establishes genetic proof whether a man is the biological father of the individual in question. There is need for use of more than one loci probes to make sure there is no error and that the results are 100% accurate.
There is the application of more than one single locus probe in the actual paternity test as one receives half of the genetic substances from the mother and half from the father. There is more than one probe that is needed to examine both parent's identity.
Or it can be said that the locus probes are utilized to determine various intervening repetitive sequences of DNA that are situated in different chromosomes and leads to the production of 30 and 20 bands, thus, one can avoid the chances of a similar pattern due to multi-band patterns.
