  We compute two-loop corrections to the vector current matching coefficient
involving two heavy quark masses. The result is applied to the computation of
the $\Upsilon(1S)$ decay width into an electron or muon pair. We complement the
next-to-next-to-next-to-leading order corrections of Ref. arXiv:1401.3005 by
charm quark mass effects up to second order in perturbation theory.
Furthermore, we apply the formalism to $\Gamma(J/\Psi\to \ell^+\ell^-)$ and
compare to the experimental data.
