Examples of dual core connectors and connection systems are disclosed. In an implementation, a dual core connector comprises a plug assembly and an engagement assembly, the plug assembly comprises a housing and ferrules. The housing has a through hole that penetrates through a first surface and an opposing second surface of the housing. The ferrules are both located within the housing and extend in the length direction of the housing, and axes of the ferrules are separately located at two sides of the through hole. The engagement assembly comprises an engagement member and a shaft body, one end of the shaft body is connected to the engagement member, and the other end of the shaft body is rotatably connected within the through hole, and when the shaft body is rotated relative to the housing into a locked position, the shaft body and the housing can lock together.