Those all look like sata power plugs to me, unfortunately if they are all on the same lead coming from your psu, then no matter how many adapters you have you will still risk heating up the single strand with all the sata connectors on it.
It may be easiest just to go for the most powerful card you can with a single PCIe connector, but depending on the load distribution it is very likely one of the 6 Pin sockets will draw a lot less than the other.
If you have already ordered the 2x6pin card then you may be able to return it, or if you are prepared to take the risk you should definitely monitor how hot the wires get by touch when the card is stressed or gaming. If you feel the main Sata strand wires are getting too hot then swap the 6pin plugs around and see if it makes a difference.
In my case it was the 6 pin socket closest to the the rear of the case (furthest from the end of the card, I know they are right next to each other) that pulled the most current, but as you can see from the french charts I showed you, different cards will demand different loads from each point.
If all else fails and you are determined to have the 270, then you may want to invest in a modern PSU that has 2x 6 pin connectors by default.