345 Hemi?

Is a 05 SLT ram 1500 5.7 hemi a 345ci/345hp engine? Also............what is the overall advantage of duel spark plugs per cylinder?

Yes and Emissions. Dual spark plugs allows for faster ignition without having to advance ignition timing, resulting in a more power/less emissions combination.
The 345hp rating is on Mid-Grade Fuel, only about 330hp on regular.