I think if you look more closely you will find that there is only one, and it is on the front head. It drives the water pump.
I also think there is some confusion between drive belts and timing belts. Timing belts drive the cams which must be kept in proper relationship to the crank so they are notched and have notched pulleys and thus are called "timing" belts since they keep the cam in "time" with the crank. Drive belts or accessory belts drive the accessories such as the alternator, air conditioning compressor, power steering pump, and water pump. Most drive belts today are of the "serpentine" variety because of how they drive multiple items and "snake" around. Serpintine belts are also wider and have multiple "V"s where the old "V" belts only had one large "V".
Did I succeed in confusing you more?
