From Hexx's "Mirror Rules Clarifications and Excuses" thread...
4) "What's the point of the DN" 2 almost simultaneous complaints- DN has a few drawbacks attached to it with few bonuses
(at least until the DNH arrives) Soo- a DN that kills someone or forces them to disengage inflicts twice the disengagement penalty.
(1hr/kill 2hours disengagement) The other sides DN is immune to this. (So an elte player in a DN can't chase off a newb in the other one)
Reading this, I see the following:
Early Fed DNs are weak. The DN / DN+ are nothing more than CC+s on a DN-hull. The DNG is a bit better, but not a ton better...
Therefore, to encourage flying the DN till the "useful" DNH and DNL came out, Hexx added the above rule.
If you read it close, it says losing to the DN doubles the disengagement penalty (ie, a CC+ that is killed by the DN is hex-banned for 1 hour and a CF that runs from the DN is hex-banned for 2 hours...)
In a DN on DN battle, standard rules apply...