Well, I have a short answer for you. Yes.
Guinea pigs are prey animals and thus they are prone to leaving "beans" everywhere. When they are picked up, their automatic thought is worry even if they love you. I mean, you're a human, an ape sized creature and you are picking them up. It has to be a little frightening. So let the beaning start!
I had one pig that it was uncomfortable for him to go to the bathroom and he would sit on me and look at me and leave a pile in my lap as if I was helping him do something difficult.
With another pig I had, my mother and I had a blanket on the couch and we were on each end. He was having a regular poop fest, and my mother was picking up the beans, and the little guy didn't want me to be left out, so he ran into my hand and left one there!
Guinea pigs do eat their beans as they contain nutrients, so I think that's what the little fellow was thinking was going on when my mother whisked them away so promptly.
There's really no way to keep them from going to the bathroom everywhere. You can collect their beans and use it as fertilizer. The best way to do this is to use a blanket when you hold a guinea pig and collect the beans in that.
If you're a true guinea pig person, you'll find beans everywhere. I was in Europe one time and found one from my pig in my suitcase. *sigh*. You'll find them in your shoe, in your bra, in your pockets, in your car, in your purse. It's like they enjoy kicking them out of their cage to be found elsewhere!
So, yes, it's normal for a guinea pig to poop A LOT, and there's not much you can do to keep them from pooping everywhere except hold them in a blanket.