since they're made out of natural materials, i wouldn't be alarmed by little variations in the leather feel. different skins may work better with different dyes, or they may have changed leather suppliers from season to season if your two spys are from different seasons. in fact, i think i've heard something about two different leather varieties being available for spys, but i don't know much about that.
BTBF, I wouldn't worry too much about it. The spy texture is "embossed" somehow, and it varies a great deal from bag to bag. I have two bags from S/S 05 (green and sequinned) and there's hardly any texture on the leather at all compared to my petrol.
They changed the leather they used.. I forgot from what to what exactly, but that changed it, because the older one scuffed easier and alot of people complained about it. Like my cousin in law has an older one, and hers looks beat up and scuffed for days, and the SA told me they changed it.