I think high crankcase pressure (from excessive blow-by or a malfunctioning PCV system) does though and I think if the oil was filled up to the rear and front main seals then it would seep out of them. I also feel that a high oil level would have a negligible effect on how much pressure is made because the pressure difference in a couple inches more of oil is very small I would imagine. The oil pump also has a pressure regulating spring that I believe would compensate for that VERY small increase in oil pressure due to level. What you might notice if you over filled is your pressure may stay high for longer after you first start it because there's more oil to warm up.
"The dreaded 2nd windshiled wiper swipe when you turn it off its almost like tis showing you that it's boss, and it doesn't have to stop when you tell it to :("-College Boy