Andrei,

At first glance all three look to be original, however, I don't like the placement of the ring on the third example,
it seems to sit too high above the frame. The examples that I have all have the suspension ring mounted almost centered on the top lip, like your first and second examples. The big weight difference gives me cause for concern too. Are you certain the iron insert is a seperate piece?

If that one bothers you my best advice would be to return it.
There are still plenty of good EKII examples out there that don't need any special explanations, whether it's original or not. Good hunting!

Joe, thanks mate.

Best!

Bill