12 volt rail question

[Trunkey]

Where a psu has a single 12volt rail is there any point in using two PCIe power leads for the gpu as they would be coming from the same bus. Or is that not quite what single rail means?

 

[Tealc]

Same current draw to the PSU.

The idea of using two cables is to share the current between two cables (less voltage drop if current is shared).