I will do MY BEST to help unravel all of this.
Ron (Head Writer of GH) asked the question "When have you seen anyone with Fluke/Luke at the same time"?? You know me, I've gone back and it's true--there has never been another person with the 2 of them at once.
We HAVE seen Dante in the basement, but he saw the orange jumpsuit, then was knocked out. He never "saw" Luke while he was down there. When he came to, he saw Bill's bones.
So, for example when we saw Luke spit out the pills, it was Luke...Fluke hadn't been switched yet and wasn't at the Q house. Helena came in and as she explained, she saw that "Luke" had tried to escape (which wasn't in their plan) and she pulled a knife on him to "get the other one back". It worked. She walked out and when Alexis walked in, "Luke" had switched to Fluke.
I hope this helps. I have no idea how long Fluke has been around, but I'm imagining for awhile. We'll delve into his childhood soon and get some answers. We personally haven't seen Luke lose track of time on screen. He hasn't been all "What the hell" that we've SEEN ever before.
So, yes even the DID will have some holes but I can't find any thing to dispute the fact that Luke has been "Split" for the past year.
I do wish that they would have gone with an diagnosed Schizophrenia. It would have been way more interesting and not been done before (that I know of) on soaps.
I'm having some trouble with all of this (as you know) because of the tone TG sets with the dual Luke's. I do feel at times, he's expressing his disdain for the years he spent with the character and the fan hooplah over Luke. But, maybe that's just me reading into things too much Who knows. You'll hear more for Sunday Surgery!