It’s not only consumers who appear to prefer Apple’s iPhone devices that use Google’s Android software to Research in Motion Ltd.’s BlackBerry, but also skeptical investors, according to Bloomberg News.

Bets against Research in Motion stock–known as taking a short position–have doubled since April, meaning that investors believe the company’s stock will continue to decline, the story says.

Short interest in RIM climbed to 31.1 million shares as of Aug. 31, more than double that of April 15 and the most since July 2007, the story says.

The BlackBerry’s Torch, a touch-screen model that hit stores last month, has attracted lukewarm sales and received mixed reviews, the article adds.