  We show that two Alexander biquandles M and M' are isomorphic iff there is an
isomorphism of Z[s,1/s,t,1/t]-modules h:(1-st)M --> (1-st)M' and a bijection
g:O_s(A) --> O_s(A') between the s-orbits of sets of coset representatives of
M/(1-st)M and M'/(1-st)M' respectively satisfying certain compatibility
conditions.
