So this doesn't stack with war. Does that go for all passive abilities? Like the magic up on the mages. Thats kinda weak. Square couldn't figure out a new name for the skill so they just drop it when you get both. If I am a lvl 20pld and a lv1 10 war I want lvl 10 war abilities! That is messed up. It kinda prevents from some job/sj combo's from getting too strong I guess. O well. Live long and prosper.
Yes, any abilities with the same name do not stack (because they are the same thing).
And they did some of this for a reason. Although I do wish you got both two-hours (kinda sucks to be a Dragoon and not be able to have a dragon if it's only your sub, should have made it a passive and given them a diff 2-hour). I do see some logic in not giving two 2-hours (imagine a Mkn/War using both thier 2-hours *shudder*)