I would call the current Perl Monks voter interface a modified butterfly. A butterfly ballot occurs when a button or recording mechanism or punch hole is placed in between two labels. Only one of the two adjacent label is the applicable one, however.
Some users, including me, may only see the ++ label and button immediately to the right of it. We are exactly like the Palm Beach voter-victim who said that he saw the label "Democratic" and a punch-hole to the right of the label. He further knew that under Florida law the second punch-hole on a ballot must go to the largest out-of-power party (which in Florida was the Democrats.) So he punched the hole to the right of the word "Democratic," but surprise! The user was supposed to read the other labels first. Bad design.
The point is, the user looked at the interface in a different way than the designer intended. Good interface design is as unambiguous as possible. It permits even a user who only looks at part of the interface to make a wise choice.