RichardM:... because the only way the vote wouldn't be valid is if you tried to vote more than once every 24 hours at that point.
That is clearly the intention, but it's apparantly not how it works. I didn't go through that list of vote bookmarks more than once every 24 hours, since the vote feedback clearly tells me when I can vote again. And whenever I accidentally voted 'again' for a comic, and got no error message, only a few hours would've passed. Which should have been enough time for any previous vote to have been registered, but not enough time for the accidental vote to be valid. I used to think that maybe my dynamic IP had changed for some strange reason, but apparently my trust in your script was misplaced.
The first vote in my list of bookmarks seems to work every time, but every vote after the first one seems to fail. As if I'm only issued one captcha at a time or something, instead of one per page. Despite the character images and buttons being different for every page. Though when I experimented with multiple votes (one page at a time) until I got the error result, it took 3-5 votes until the vote seemed to count, so apparently there's more to it than just opening a single vote page at a time. And if the cheaters read this, I guess you'll just have to take your 'security through obfuscation' one step further, and fake the vote traffic page as well?
Would you consider a more effective way of voting for multiple comics, such as having a page with check boxes for favourite comics which has to be manually clicked/checked every day, and then voted for with a single final click of a button? In the vote traffic I saw that a few others seemed to have no referrrer, as if they too voted through bookmarks, and perhaps there would be many more if the vast majority of their votes weren't invalid without them knowing it?