Both men set their fastest times in the morning, with Haryanto just edging proceedings with a 1m39.129s - three tenths of a second quicker than last year's pole time.
Rossi - quickest on the opening day - finished just four hundredths of a second down the road, with both men establishing a comfortable gap to the rest of the pack.
Julian Leal wound up as the pair's closest challenger, just ahead of last year's European Formula 3 champion Raffaele Marciello and DAMS' title-hopeful Jolyon Palmer.
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2012 GP3 champion Mitch Evans and McLaren protege Stoffel Vandoorne were the only other drivers able to crack the 1m40s bracket.
Temperatures rose in the afternoon, but with the majority of the field switching focus to long runs the times were significantly slower.
MP Motorsport's Daniel de Jong wound up fastest with a 1m40.508s, followed closely by Johnny Cecotto and Leal.
Pre-season testing concludes on Friday, with the 2014 season opening at the Sakhir track on April 5-6.
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