It is shown that for R an
integrally closed domain then M ⊕ X≅N ⊕ X implies M(t)≅N(t) for some positive
integer t for all finitely generated S-modules M, N, X whenever S is a module finite
algebra if and only if one is in the stable range of the integral closure of R in the
algebraic closure of its quotient field. In particular, this holds whenever R is a
Dedekind domain with all residue fields torsion. This extends work of Goodearl, who
showed this holds for module finite (and more generally, finite rank) algebras over the
integers.