Same exact running shoe- but feels different ?

Weird thing with my running shoes. I found a great pair of Asics and they were so comfortable I decided to buy 2 more because the style was to be discontinued. I found new ones on eBay and bought them. They must be narrower up by the pinkie toes because it is painful and terrible for walking... I just keep wearing the older, dirty ones. How could the same brand, model, size be so different ? Has anybody had this experience. I also bought one pair in a different color and they felt different too.....