Why do the good ones always seem to fall on the same night? This week, two biggie beatsmiths break it down in Hollywood, and — as has often been the case lately— dance fiends will be split on which to hit. At King King, the shindig known as Incognito closes out ’09 with its last event of the year, headlined by Chicago house “godfather” Marshall Jefferson. MJ, known for seminal tracks such as “The House Music Anthem,” is credited with not only introducing the early “acid house” genre to the masses but also being an instrumental innovator (adding elements like piano accompaniment to his dance cuts). Whatever he spins, it’s an essential house head happening. 6555 Hollywood Blvd., Hlywd.; incognitola.com. Down the street, more monumental dance-floor moments are sure to take place, when Control welcomes megaproducer/DJ Armand Van Helden as part of its one-year anniversary bash. The guy has worked with everyone on hit remixes, but it’s his knack for pleasing a crowd while pushing them in a club environment that put him on the map in the first place. Despite the night’s name, his set should be outta control. Avalon, 1735 Vine St., Hlywd.; myspace.com/controlfridays. Both clubs on Fri., Dec. 18.