What now
 

Watching a high school playoff game (NFHS rules)
Left field (300') has fence 20 feet high to keep balls out of neighbors yard
Ground rule is batted ball must go over fence for home run
Not just above the lower (8' high) wood fence the cyclone fence attach's to.
Sit
Don't remember # of outs
Runner R2 & R1
Batter hits ball 3/4 of the way up the fence down the left field line
PU has catch/no catch
As ball rebounds off of fence
R2 rounded 3rd
R1 just touching 2nd
A second ball now falls from the fence ten feet from the game ball
(must have gotten stuck at an earlier date)
There appeared to be no confusion of which was the game ball..................

As BU (in C position) or PU what do you do in this situation?
What rule do you use for your decision?

I will probably will never have this happen to me, but would like to have some type of answer in my knowledge base just in case

Everyone knows which ball is in play - keep playing.

You let the play go b/c in your words "There appeared to be no confusion of which was the game ball" and then at the end of the play have the other ball removed.

OBR 9.01c
FED 10-3(g)

I would see how the other ball affected the play of the outfielder, who would be the defensive player most likely to be confused, and whether any of the runners slowed. If everyone just ignored it until the end of playing action, so would I.

If either team stopped playing, I'd kill it and rule it a two-base award (ground rule double) to avoid putting either team at (more of) a disadvantage.

yep, me too.

Be kicking the BU for not climbing the fence and removing all baseballs. Rule 9.01(c):p