just an odd thought, maybe the grits are different? The older one could have been smoothed out by use, meaning the new ball has better traction? Plus maybe the coverstock near the surface has lost some track due to absorbed oil?
I've actually had several different balls where I bought a 2nd one with the same pin, drilled them the same, and the 2nd one always seems like a stronger ball, until I get 30 or so games on it, then it tames down and behaives like the first one, just slightly stronger. However, as they approach the same number of games, the reactions get closer and closer to being the same. There is such a thing as new ball carry.