Several other examples of this close binary interaction are known in our solar system.
Binaries appear to be very common in accretion disks, and the members appear to often continue growing (by accretion)until they touch. Several examples are known in the asteroid belt.
Contact binaries in stellar systems seem to occur when one or both stars grow into their Roche lobes until they touch, and actual matter transfer can occur. In these cases, the individual members were originally quite separate, but after swelling up actually touched.