Ah.. I did not read carefully.... parallel... Yup, you are right, in parallel it will be less restrictive, but also less effective.
I know there is a lot of confusion about the effectivity of the water felocity in the radiator.
(I had it, and posted some questions about it. At the end it turns out
Thrust me if I'm telling you that at a higher speed the heat disapation of the water to the radiator is a lot better. In Parallel the felocity is about half.
This is also the reason one double rad will work better then 2 in parallel
Space is most of the times an issue to go for a 2 rad setup.