The competition rules state that away goals are "counted twice", which in typical football governance fashion is a nicely ambiguous way of stating things. "Counting twice" could quite easily be taken to mean "counting double", however, seeing as "twice" and "double" are synonyms.
http://cup.efl.com/competition/rules/#13
Rule 13.5.
So, whilst it is a preposterous formulation of how to achieve the tie-break, I think by the letter of the law, if we were to lose 2-1 after
extra time on Wednesday it would be legitimate to say we won 3-2 on aggregate due to our away goal being counted twice.