The only reason why anyone would want to use two 12V-2x6 cables is to have a PC with two Nvidia graphics cards but given that ...

A prototype removes the need for a GPU power cable, improving airflow. The new 12-volt motherboard features a 50-pin design to supply 1500W to multiple components. The prototype requires a BTF3.0 ...

In theory, every current pin can supply up to 575 watts, which is important for powering the GPU efficiently. However, problems can occur if the cables are cut internally or not seated properly.