I think the extra spread has to do with atmospheric conditions and projectile time of flight.

Since the projectile is slowing down as it travels down range, it takes longer to travel the second 25 yards than it does the first, so the ball has more time to wander off the intended course and consequently misses by more than double the error of the 25 yard target.

Throw in that if you're shooting outdoors, there's always something going on with atmospheric conditions. Maybe a puff of wind, a change of direction or a change in pressure. Add that bit of unknown condition to the extra projectile travel time, and viola, you just missed the target!

John