Ambrose of Milan
Catena Aurea · Matthäusevangelium 1
So all the generations from Abraham to David are fourteen generations; and from David until the carrying away into Babylon are fourteen generations; and from the carrying away into Babylon unto Christ are fourteen generations.
(ubi sup.) Again, from Jeconiah to Joseph are computed twelve generations; yet he afterwards calls these also fourteen. But if you look attentively, you will be able to discover the method by which fourteen are reckoned here. Twelve are reckoned including Joseph, and Christ is the thirteenth; and history declares that there were two Joakims, that is two Jeconiahs, father and son. The Evangelist has not passed over either of these, but has named them both. Thus, adding the younger Jeconiah, fourteen generations are computed.