I have a 2 element boiler, both at 2.7k. I used the same socket and blew it.
Use diferent sockets for sure.
On another note, using 2 elements to boil causes a lot of evaporation, up to 30% i found. Better to use both to get to cold break, and then knock one off.
Just used my Double Element boiler for its first full brew. I was great! Up to a nice rolling boil in 25 minutes. I was then able to drop the original element down to 50% with the control to maintain a nice boil.
I had no problems with using the same double socket.
Looks like a nice job freedgull, but out of habit from my daytime role as a electrical engineer type, I saw bits of possibly energized metal on the exterior of that element you swiped from the kettle. You might want to cover those metal bits in some RTV waterproofing compound both to protect you from inadvertent contact and the element from potential boilover or spillage.