Calculate right number of supply and ground contacts per connector
Variant 1 is correct as far as the maths goes.

5 VCC pins and 5 GND pins, because each pin can handle 2A, so 2A × (5vcc + 5gnd) = 20A.

That's like saying &quot;I have a container that has five inlets and five outlets. Each inlet has 2 L/s going in and each outlet has 2 L/s going out. Therefore the total (water) current = 2 L/s * (5 in + 5 out) = 20 L/s. It's not. It's just 5 x 2 = 10 L/s in and the same out.



simulate this circuit &ndash; Schematic created using CircuitLab
Five inputs with 2 A each = 10 A. Current out = current in.
As @vir has pointed out, while the individual contacts may be rated at 2 A there may be total current rating as the sum of the contact resistance heating may have to be taken into account.