The Fantasia vs. Diana vote on ''American Idol'' two months ago may have been close, but their rematch at the record store was not. ''Idol'' winner Fantasia Barrino's single ''I Believe'' more than held its own against Diana DeGarmo's ''Dreams,'' even though ''I Believe'' had already been in stores for a week. ''I Believe'' (backed with ''Chain of Fools'' and ''Summertime'') remained atop the Billboard singles chart and sold another 81,000 copies, according to SoundScan, down from 142,000 last week. ''Dreams'' (backed with ''Don't Cry Out Loud'' and DeGarmo's own version of ''I Believe'') debuted in second place, selling 65,000. At least both singers can say they outsold reality TV newcomer Ashlee Simpson. Despite her current MTV series, Jessica's sister sold just 8,000 copies of her first single, ''Pieces of Me,'' though that was enough for a third-place debut.