After checking for a bit, here's what i saw: There's a time skip of two months since Deryl turned into a monster, then there's 1 week of wait until we go to the mall and get caught by the police, and then we run from the police for like a week in which we also fight Valravn and forcefully join H.E.R.O and then we wake up the next day after beating Valravn and meet Del. That would mean that if Del was Deryl's clone he could have only realistically joined hero 2 months and 2 weeks before we met him, while training for 2 months and 1 week, and the other week actually fighting monsters alongside Laurie, because after reading it again, Deryl in fact says: "Nah man. I just don't have the focus to control more than one body at a time." After his fight with the MC.
So, in conclusion, I guess it could technically possible for him to be a clone, but it's kind of a reach imo, not only would he have to train for 2 months instead of 1, but it would mean that both Laurie and Del are saying he's been there for a few months instead of just saying 2 months, which would be kinda strange to me, I mean, when I think about the concept of "a few months" I imagine at least 3 months, if not 4.
That's also considering that Deryl used all of the time he had available, which would also be unlikely to me, I mean, from what we have seen he's moving behind Ella's back, so he would probably need at least a few days to make a clone of himself and sneak it out of their hideout undetected, something that would further shave off the posible time for Del to be around, this is assuming that literally the first thing Deryl did when turned into a monster was think of a plan to do whatever the fuck he wants to do with MC, instead of getting used to his monster body, his new power, and regaining control of himself (If he ever lost it, who knows, maybe he underwent the perfect monsterification for all we know).
Maybe Del is in fact a failed clone he tried to make while on his first evo and that's why he looks like a kid as someone said bebfore, so Deryl just made use of that and my last point is invalid, but fr tho, in what world does "a few months"=just 2 months lol? Unless I'm missing another time passing instance, in which case, I'd appreciate it if someone could double check for me..