The Dahlquist DQ-LP1 provides an 18dB/octave (3rd order) active low-pass filter, and a 6dB/octave (1st order) passive high-pass filter. So no, the DQ-LP1 will not give you the 6dB/octave boost you need to counteract the dipole cancellation in your subs (I know because I have dipole subs and speakers, and a DQ-LP1).
However, Rythmik Audio, in conjunction with GR Research, has designed an OB/Dipole sub, and the plate amp included in the sub kit DOES include a 6dB/octave "shelving" boost circuit---specifically to compensate for dipole cancellation. The plate amp is available separately, a mono 370 watter with a lot of great features and controls specifically designed for subwoofers. The x/o frequency is adjustable from 40Hz all the way up to around 300Hz---very versatile. Look on the Rythmik website for more info.