It's a normal key for some ISO layouts. I have one just like it on my AZERTY (Fr) Olivetti.
I thought it was pretty awesome, too.
Looks like the second one has all the A-Z keys right for Us-ANSI. With a moogle kit, you could really have something, I think.
As of now, the only have 1 of the AZERTY one and 2 of the QWERTY one.