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It was already stamped in the first place, as said before, so it'd be 2/2 after applying it, if you don't think you'd have to take a second look to corroborate, that is.
Statistically speaking no, especially when ignoring specific cases like RNG Manipulation (certain shiny + IV combos are only possible on certain TID + SID combos, more notably when not breeding), or the Cute Charm bug. The number of PIDs that are shiny are always the same per save file given how...
Okay, as the Tera stuff is coming up, and then NDPL is coming up, this isn't really practical for some months, if you have the time after NDPL feel free to shoot me a message at that time, however.