<< KnotTheory`

MVA[K_] := Expand[Simplify[
(MultivariableAlexander[K][t] /. t[1] -> t)*(t^(1/2)-t^(-1/2))
]]

MVA /@ AllKnots[{3,7}] /. t[1] -> t

Alexander[#][t]& /@ AllKnots[{3,7}]

(MVA[#] == Alexander[#][t])& /@ AllKnots[]