What is the difference between connecting an adapter for add. video card power through one molex and two?

Question

Iron

OS: Windows 10 Pro;
CPU: Intel Core i5-4440;
RAM: 8GB;
Motherboard: MSI B85-G41 PC Mate;
Hard drive: WDC WD10EZEX-75WN4A0 (1 TB, 7200 RPM, SATA-III);
PSU: FSP 350-60GEN;
There is an adapter from molex to 6pin add. video card power supply:

There are 2 lines from the power supply unit (I don’t know if I’m calling it correctly, correct me if that): on one molex and power for the drive,
on the other two molexes. A hard disk is connected to the line with two molexes and, until recently, an additional one was connected. power supply for the Asus Radeon R9 270 video card (Through one of the two molexes on the adapter, the second one was not connected).
The card flew off twice, it was raised by warming up and it worked further, on average for a year, recently it flew off again and it was decided to leave it alone and take it to replace the MSI GeForce GTX 1050 Gaming X. There were no problems between the "departure" the card worked perfectly, did not overclock, after the first "flight" the settings were always such as to keep its temperature no higher than 60 degrees.
Here, in fact, are the questions that I have accumulated today:
Is it necessary to connect both molexes to the additional adapter. nutrition?
What will be the difference if only one is connected?
If it is necessary to connect both, is it better from one line, or from different ones?
The power supply is old, I want to make his life easier, so I wonder if there is a difference for him how the extra is connected. food, or the load on it is the same?
The 1050 card is not demanding, without overclocking it should have enough power from the motherboard, and yet I was very interested in these questions.
UPD:
If someone can, explain on your fingers (I know that I'm dumb, but I just can't form a complete picture in my head) Let
's say 3 states, how they differ from the side of the video card and from the side of the PSU (how much energy the video card receives, what is the load on the PSU (relatively):
1. Only one
molex is connected 2. Both molexes are connected from the same line
3. Both molexes are connected from different
PSU lines:

Answer 1

It often happens that it is necessary. Otherwise, the map will not start. The adapter was originally conceived in order to be able to connect different PSU lines, dividing the load.

Answer 2

Load capacity of wires and connectors. Through thin wiring and one connector, you can’t transfer much.
It doesn't matter to your card.