actually that second doppel card isnt necessary if youre planning to use a black smith to do the dirty job. You can achieve 190 aspd (mas aspd) with one doppel, berserk potion, adrenaline rush, and about 30 agi if i am not mistaken. That is why people use the DBSS and not DDBS.
it's a choice
DDBS pros = bers pot and u are 99. u dont have to use adrenaline rush, your aspd wont reduce if u get agi down (especially to blacksmith when u dont have boost cart to cancel agi down), invest the rest into dex and u can use that weapon to level novice, acolyte, merchant, swordie as well
Increases minimum damage of attacks
* Level 1 weapons: minimum damage +1
Every 5 DEX: melee damage +1
let say a typical BS/WS have 130str kaho + 9x str + bonus
u only need a few extra hit to kill dulahan which is only 1-2 sec extra. 1 sec at 190aspd is 4 hit?
cons = u do lost a bit of damage and maybe it's harder to resell