So I realize that the Get'ikku proc is stupid powerful as is - does having 2 give any notable improvement, or would it be better to have a stat-stick in my other slot?
Yes having two is def in a lot of cases the way to go however, if for example you have two 355 geti and the 370 heroic thor (Taloc) mace ld replace the second geti with the mace. However unless the item has haste on it and 15-20 ilvls advantage Geti is typically stronger. Although the proc just refreshes the duration it does allow it to proc more often since it can now proc on off hand melee attacks as well.