Rule variations between PF1/3.5 - Stacking

[ixrisor]

You cannot add a single bonus twice, any more than you can claim arbitrarily high bonuses to attack rolls by adding the bonus from Weapon Focus multiple times (okay, that would also fall foul of the "same source" rule, but there is a fundamental reason than that why you cannot do it).

You can definitely add constant numbers to your armour class (or attack bonus or whatever) more than once, so why would you not be able to add variable bonuses more than once? For example, a manifested ghost with battle dancer levels should add its charisma to its armour class twice, once as a deflection bonus and once as an untyped bonus.