Talk:Lulu/@comment-4888212-20130730201256/@comment-1920011-20130805200925

If 2 slows affect a champ, the stronger one gets full effect and the next is reduced by 65%. http://leagueoflegends.wikia.com/wiki/Movement_speed#Slow_stacking

Definitely not worth putting both on the same target, spread the slowing effect instead.