If the two bodies are exactly the same size and shape, the heavier of the two will reach the ground first. Here is why.
Descending through a gravitational field at a certain velocity releases power in the amount (mass x gravitational acceleration) x velocity in both falling bodies. Since their mass is different, more power is developed by the heavier object, at the same velocity through the air.
That velocity creates air friction on the bodies, which then applies a force to each in the amount (drag coefficient x cross-sectional area x velocity ^2) which opposes their motion through the air. Since their shapes are the same, so will be their drag coefficients, and since they are the same size, their cross-sectional areas will be the same too. This means that the atmospheric drag force on each will be the same, at the same velocity.
The power being released by falling is available to perform work by pushing the bodies through the air. Since the power generation rate of the heavier object is bigger than that of the lighter object, it can perform work against the atmosphere faster, and so it will fall faster- and reach the surface of the earth sooner.