does my 2007 dodge ram 1500 5.7L have 2 spark plugs per a cylinder

Off the top of my head (without reference books) I think your engine does have 2 plugs per cylinder. You mentioned sputtering after an exhaust mod - do you mean the sound or the actual performance?(buck, jerk, hesitation) The 5.7 (if memory serves) has copper core plugs that need replacing more frequently than most vehicles. Check the owner's manual on Tune-up intervals.

not sure about the '07, but the '08 has 2 per cylinder. uses cheap champion plugs. need to change them about every 30k miles. changing the exhaust shouldn't make engine sputter.

The 2007 Hemi requires copper plugs on the intake side and iridum on the exhaust side. Total of 16 plugs. If the spuddering started after the exhaust change, a computer tune may be needed after removing the back pressure of OEM exhaust system.