A receptacle connector for two types of plug includes an insulative housing defining a front mating port and a rear connecting port along the front-to-back direction, the front mating port defining a plurality of upper passageways and a plurality of lower passageways with a receiving slot therebetween in the vertical direction, the upper passageways being respectively offset from the corresponding lower passageways in a transverse direction. An IMLA (Insert Molded Lead-Frame Assembly) assembled within a space of the rear connecting port and including a plurality of wafers stacked with one another along the transverse direction, each of said wafers including an insulator equipped with a front upper contact disposed in the corresponding upper passageway, a rear upper contact located behind the corresponding upper passageway, a front lower contact disposed in the corresponding lower passageway, and a rear lower contact located behind the corresponding lower passageway.