Three closely related double perovskites (DP) based on the 5d2 ion, Os6+,Ba2MOsO6, with M=Mg, Zn, and Cd have been prepared and characterized using x-ray (XRD) and neutron diffraction (ND), dc magnetization, heat capacity, and muon spin relaxation (μSR) techniques. All three are cubic, Fm-3m, at ambient temperature from XRD with Δd/d∼5×10−4 resolution. For both M=Mg and Zn, ND data at 3.5 K and lower, Δd/d=2×10−3, resolution show no signs of a distortion. The results are compared with the known DP material, Ba2CaOsO6, which shows antiferromagnetic (AF) order below TN=49K and a moderate frustration index, f∼4, (f=|θCW|/TN), where θCW is the Curie-Weiss temperature. Ba2MgOsO6 with a unit cell constant a0=8.0757(1)Å, 3% smaller than for Ba2CaOsO6, also shows Néel order below TN=51K with f∼2. However, Ba2ZnOsO6,a0=8.0975(1)Å, 0.27% larger than Ba2MgOsO6, does not show Néel order from either heat capacity or μSR data. A zero field cooled/field cooled (ZFC/FC) irreversibility occurs near 30 K and a broad heat capacity anomaly is detected at a similar temperature. The μSR data are consistent with a weak spin ordering with an onset below 28 K but with a coexisting dynamic component. Ba2CdOsO6 with a0=8.3190(1)Å, 0.5% smaller than Ba2CaOsO6, shows no evidence for any type of order/spin freezing to 0.47 K from any of the measurement techniques applied. The results for M=Zn and Cd appear to lie outside of the mean field theory of Chen and Balents [Phys. Rev. B 84, 094420 (2011)10.1103/PhysRevB.84.094420] for cubic d2 DP with strong spin orbit coupling, but Ba2MgOsO6, along with Ba2CaOsO6, is likely one of the three predicted AF phases. The remarkable contrast between the doppelgänger pairs M=Mg/Zn and M=Ca/Cd may be traceable to differences in electronic structure of the diamagnetic M ions. All of the super-super exchange pathways in these DP materials involve Os–O–M–O–Os linkages.