Nope doesn't stack lol

Edit: Now that I think about it...I DO have an idol that adds like +5-10 spell crit strike rating to my aura...I haven't actually WORN it while boxing(I only did during raids occasionally; I used Wrath idol for Curator, Starfire Idol for almost everything else, and nowadays I wear the "Chance on Moonfire cast: +140spelldmg for 10sec" badge idol), think I'll try when I get home and see if my "Improved" Aura stacks with their basic auras lol