Duncan do a stacked P-90 as well.  
And DiMarzio have several models which are scaled down side-by-side humbuckers in P-90 covers (with 12 visible polepieces).  Some are meant to sound like P-90s, others are versions of regular DM humbuckers (Tone Zone, Super Distortion) for P-90 guitars.  They don't do them with dogear covers though.
None of them, including the P-100, really sound like P-90s, unfortunately.  I like hum-cancelling Strat and Tele pickups, but you can't beat a "real" P-90.  I just have to live with the hum, it's part of that raw tone.