We extend the chiral Lagrangian with heavy quark-diquark symmetry to quenched and partially quenched theories. These theories are used to derive formulas for the chiral extrapolation of masses and hyperfine splittings of double heavy baryons in lattice QCD simulations. A quark-diquark symmetry prediction for the hyperfine splittings of heavy mesons and doubly heavy baryons is rather insensitive to chiral corrections in both quenched and partially quenched QCD. Extrapolation formulas for the doubly heavy baryon electromagnetic transition moments are also determined for the partially quenched theory. © 2006 The American Physical Society.