A system for asynchronously delivering reductant from a reductant storage tank to a first selective catalytic reduction system and a second selective catalytic reduction system included in an aftertreatment system includes: a reductant insertion assembly fluidly coupled to the reductant storage tank, the reductant insertion assembly configured to be fluidly coupled to each of the first selective catalytic reduction system and the second selective catalytic reduction system, the reductant insertion assembly including a first injector fluidly coupled to the first selective catalytic reduction system, and a second injector fluidly coupled to the second selective catalytic reduction system; and a controller communicatively coupled to the reductant insertion assembly.