A source close to Bassett, 47, told People magazine the babies are due "in a couple of months."
A publicist for the star of "How Stella Got Her Groove Back" and "What's Love Got to Do With It" had no comment, People said.
Vance, 45, who starred "The Preacher's Wife," and Bassett were friends for many years before going on their first date in 1996. They became engaged in 1997.
Celebrity Families of 2014 [PHOTOS]