It's official, but i think it's very unnecessary for players, very very annoying that itens occuping storage slots.
in jRO, they have a NPC to "stack" that separated itens, because a strong demand of players, and at bRO, they do the same, but only by ticket support.
http://ragnarokonline.gungho.jp/gameguide/item/item-integration.html
I think it need a option to easy on/off at server conf, to prevent troubles and satisfaction of the players.