Are differing accounts of the same events in the Bible proof of their veracity?

For instance, differing accounts of Jesus' birth between Matthew and Luke; or differing apparitions after his death between Matthew and Luke.

Although these contradictions make it difficult to believe the Bible's writings were "inspired by the holy spirit", many theologians argue that because there are various accounts of the same underlying events, they must be true.

I am anticipating a theological debate with my father soon and would appreciate some good arguments!