Why would you not use the 2 on the same lead? Since one cable comes with 2 slots for a GPU, why not use it? It is not a problem unless you are doing some extreme overclocking. And it is okay to do it in the above configure too. You can leave them hanging.
Thank you for the quick answer! I dont think I can use the same lead.
Each of the cables has 2x8pin connectors total (1x8pin and 1x6+2. The remaining one is just 6pin, no +2). I need a total of 3 8pin connectors: one for psu and 2 on the gpu. Hope that makes sense.
Will try with the 2 cables and report back.