Yes, but Hoggard can swing the ball both ways as can Sidebottom, so the angles don't really change. It's the matter of having no pace in there.
Of course the angles change, one bowls with his left hand and one with his right, that's the angle! Sidebottom also bowled the fastest for us in the ODIs iirc, getting up to 87.
I personally believe both could play together, we've used Hoggy as our middle overs workhorse before. I chose Anderson as he has been very good this summer too, but as Evertonfan says, I'd hate to be Peter Moores, lots of selection (well in the bowling anyway, top 7 practically picks itself)