It is possible. You may have a gasket failure between the combistion chamber and water jacket. This would allow coolant into the combustion chamber without any significant mixing with oil. A compression test is called for at this point.
Yeah it just depends on where the HG failure is. Sometimes the coolant leaks into the oil, sometimes the coolant leaks into the cylinder, sometimes the coolant leaks down the side of the block, sometimes the combustion gases leak into the coolant.