  We calculate analytically the stochastic thermodynamic properties of an
isothermal Brownian engine driven by a duo of time-periodic forces, including
its Onsager coefficients, the stochastic work of each force, and the
corresponding stochastic entropy production. We verify the relations between
different operational regimes, maximum power, maximum efficiency and minimum
dissipation, and reproduce the signature features of the stochastic efficiency.
All these results are experimentally tested without adjustable parameters on a
colloidal system.
