Complex sentence: Since it is improbable that Osorkon I buried his son without leaving any grave goods from his reign, it would appear that Shoshenq II was someone else--perhaps a younger son of Shoshenq I since the tomb contained several objects naming this king.
Split into simpler sentences: Since it is improbable that Osorkon I buried his son without leaving any grave goods from his reign, it would appear that Shoshenq II was someone else. He may have been a younger son of Shoshenq I since the tomb contained several objects naming this king.