Have you taken the DNA test to see which line of the CARROLLs you match? Go to the chart at http://www.childtalk.com/History/carrollfamilydnavalues.pdf
You can see the lineage of Charles Carroll of Carrollton in the dark green section near the bottom. The profile of the descendants of both lines you mentioned should be the same or very similar to that one leading back to Daniel of Litterluna, IR.
If you send a DNA sample and see that you don't match that haplotype, then you know that you must dig harder to find another ancestry for your line.
There are several groups of DNA haplotypes beginning to form now, and soon I think we will begin to understand this surname a little better.