Not plagiarism, and maybe not even inspired. It's easy to see how both designers could reach this solution independent of each other. I think El-Khatib's is better, of course.

BTW, I was under the impression that this typeface was by James Langdon. Maybe co-authored?

Ahh, here's the answer to my question. The typeface is by El-Khatib, the identity design by Langdon.

Plagiarism and inspiration both require sturdy definitions!

I'm a bit reluctant to comment - it seems bad form to make a judgement without knowing all of the facts - IMHO there is quite a strong connection between the two designs, but just how significant is that?

It's not unusual for persons involved to turn up on Typophile to comment.

Of course, maybe the difference between plagiarism and inspiration is fairness? (which is relative...)

That would be very welcomed—to have the designers provide their own side of the story.

I think what makes me lean towards seeing it as a direct inspiration (and maybe too much) is the fact that the Twin typeface has been in use and appearing on many design blogs as early as July 2010, whilst The Capitol identity appeared locally only early this year...

It also seems too convenient that only the C, O and I (although you couldn't really do that character differently) are exactly the same in their construction (the word, The Capitol is in a different style obviously but uses the same construction) as if the they were trying to avoid being exactly the same. I'm speculating here of course...