From what I've been reading, dead pixels are something that you can find in the iPod Touch, but isn't something in all of them. It might just be that you were one of the "lucky" few that happened to get two with a dead pixel.
I purchased a PSP not too long ago and it had a dead pixel in the LCD. Prior to that point I didn't even know about dead pixels as I've never experienced it with another product in the past. I actually had to return 3 before I was able to get one that didn't have a problem.
It may be a bit of a hassel to keep returning, but if you are putting that kind of money out, you really want the product to be nice and new out of the box, not with imperfections right away. Some people don't mind them, but I personally wouldn't keep one that has a dead pixel, from my understanding as long as the screen has no dead pixels in the beginning, you should not get any down the road either. I find that the when my screen has a dead pixel my eyes automatically pull to that area and it tends to drive me crazy, hence the reason I returned 3 PSPs. I'm really hoping I won't have any problems with my iPod Touch, so fingers crossed. If it doesn't really bother you, then you don't need to return it, but I think the best thing it to replace it so that your nice new product is a perfect as it can be!
Enjoy!