What evolutionary events might have led to the presence of two genomic clones in pigs, and the discrepancies in their length compared to the cDNA probe? How is this representative of a general type of occurrence in molecular genetic evolution?

Gene duplication  

Explanation:

Gene duplication is an evolutionary process that includes different phenomena such as, among others, unequal crossover, chromosome rearrangement, chromosome duplication, etc. These duplicated genes are redundant in function and therefore they may accumulate mutations such as insertions or deletions at higher rates compared to single-copy DNA sequences, thereby producing homologous genomic fragments with different lengths

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: