There seems to be a conflict between HeadSpace2 and Deko Boko. HeadSpace2 invokes the Deko Boko shortcode *twice*, which is problematical. Deko Boko has side effects (it verifies a recaptcha code, and on the second round trip, this fails).
I don't know if this is a Deko Boko bug or a HeadSpace2 bug or even a WordPress bug. I've let the Deko Boko author know about this.