spark plug screw up

I'm new to working on my vehicle and plan on doing most of the PM myself to save some money and keep my truck running better since I really haven't done anything besides oil changes since about 30K miles (now at 75K). I have a 2000 prerunner. I recently changed the spark plugs using denso PK16TR11 to replace the denso K16TR11 plugs. the difference is the new ones are platinum. they look like this picture here:
http://www.densoproducts.com/productImages/3/3289.jpg
I had the hardest time gapping them, and then I was recently told that plugs with the double "arms" aren't supposed to be gapped. so I'm trying to find out if that is true, and if so should I replace the plugs (again)? the truck runs noticeably smoother and idles lower now.
thanks.

If it runs smoother I wouldn't change them unless you have problems.