If a permanent has multiple instances of extort, each triggers separately.
April 28, 2017 · Amonkhet
A fused split spell has the combined characteristics of its two halves. (See rule 708.4.)
July 13, 2013 · Magic 2014
A fused split spell has two sets of characteristics and one converted mana cost. The converted mana cost of the spell is a number equal to the total amount of mana in its two mana costs, regardless of color.