There's that Spanish connection again, tying in with the legendary "Milesia." The tough thing with early surnames is that there is a strong element of "fashion" to it. How mine, purportedly originating with O'Tuathail, ended up three centuries later all Frenchified as "de Tottehille" has got to be due to the Norman influence. I'm sure many things English are a similar mish-mash.
Are you saying your name is O’Toole? Or Tuttle?