This Bible contradiction is from the Skeptic's Annotated Bible.

Verses

Joel

1 Samuel 8:2 View context

Now the name of his firstborn was Joel; and the name of his second, Abiah: [they were] judges in Beer-sheba.

Vashni

1 Chronicles 6:28 View context

And the sons of Samuel; the firstborn Vashni, and Abiah.