When Green Mill owner Dave Jemilo bought a second Hammond B-3 last year, he must have had nights like this in mind: the city’s two leading jazz-organ men going head-to-head, pedals to the metal. Dueling organs come up a lot less often than almost any other instrumental matchup, since a single B-3 (with its multiple keyboards and timbres) can mimic half an orchestra. But Dan Trudell and Chris Foreman make fine sparring partners. Foreman, anchor of the Deep Blue Organ Trio and Henry Johnson’s Organ Express, was inspired by Jack McDuff and Jimmy McGriff, the iconic “second wave” organists who followed the pioneering Jimmy Smith, so his florid lines simmer with blues. That contrasts neatly with Trudell’s expansive solos, which emphasize the less ornamented, less bluesy approach of Larry Young and, more recently, Larry Goldings. They’ll be joined by Andy Brown on guitar and Greg Rockingham on drums, but I’m guessing those guys will be lucky to get a solo in edgewise. a 8 PM, Green Mill, 4802 N. Broadway, 773-878-5552, $10.