Yes, the brackets were drawn weeks ago (or, more precisely, pulled from the PIAA's file of pre-drawn brackets). PIAA just has to fill in the names and release.
Officially, the ONLY time PIAA deviates from pre-drawn brackets is when 2 returning PA champs are at the same weight, both champs from last year, and both are regional champs this year. That could've happened only once this year: AAA 120 with Spencer Lee and Jake Riegel -- until Riegel took 3rd at NE AAA.
I say "officially" because no way the PIAA will hold fast to that rule with a major event at stake. For example: Gulibon's 4th state title. Zain would've been at that weight had his transfer been approved, was a returning state champ but was 3rd the prior year. Does anyone really think the PIAA would let Zain vs. Jimmy happen in the quarters or semis? With Jimmy already being a 3x champ?
Anyway, you're right, and it would be a terrible shame if Spiller and Dunn are on the same side, but far from unprecedented.