Where Have All The Afghan Voters Gone? Part II

The following report, sourced from the Associated Press, is part of a story now being picked up by the media in general.

candidates challenging interim leader Hamid Karzai (search) said they would boycott the outcome because of potential fraud in the system designed to keep voters from casting more than one ballot.
[...]
About 10.5 million registration cards were handed out ahead of the election, a staggering number that U.N. and Afghan officials say was inflated by widespread double registration. Human rights groups said some people obtained four or five voter cards, thinking they would be able to use them to receive humanitarian aid.

Afghanistan has an estimated population of 25 million.

I posted on this "staggering" number previously,but it bears repeating: Afghanistan has approximately 25-28 million people (the estimates vary), a little over half of whom - which would mean 12.5-14 million - are of voting age and therefore eligible. So why would 10.5 million registrations be "staggering?"

The 10.5 million figure will now play a prominent role in the upcoming claims of fraud, where it will do its damage, hopefully not too much.

UPDATE: This story was sourced from Reuters:

During the campaign, some candidates expressed surprise that as many as 10.5 million out of the country's 28 million people had registered to vote, and said they believed many people had received multiple voter cards.

But why would this number have been surprising?