Overlapping Spell Resistance

[Muzzy]

The rulebooks say this about Spell Resistance:

Quote:

Spell resistance does not stack, but rather overlaps.

Which is great, because stacking Spell Resistance would be very powerful. However the rulebook doesn't spell out how that overlap works exactly. Lets assume you have a Dwarf Monk, level 13. Lets also assume that this Dwarf has the alternate racial trait of Magic Resistance.

His racial trait gives him spell resistance of 5 + Level (Total: 18). At level 13 he gains the Monk ability of Diamond Soul, which gives him 10 + Level (Total: 23) spell resistance.

Mr. Evil Wizard decides to cast Magic Missile on our Dwarf friend. Now what happens? As I can see it, there are two possibilities:

1: Mr. Evil Wizard makes a roll to overcome the SR of 23. If successful the Dwarf takes some 1d4+1 damage. Otherwise the Dwarf has resisted and no damage is dealt.

2: Mr. Evil Wizard makes a roll to overcome the SR of 18. If successful, Mr. Evil Wizard has to make another roll to overcome the SR of 23. If successful the Dwarf takes some 1d4+1 damage. Otherwise the Dwarf has resisted and no damage is dealt.

Which is it?

[Quandary]

your second roll would be multiplicative stacking
(as opposed to additive stacking, like stacking AC bonuses increases one AC score)

if things don´t stack but over-lap, you use the highest relevant one (one SR could conditionally be higher vs. a specific spell type while normalling being lower for example)

the other SR is sitting there ready to do stuff just in case the higher SR is cancelled out somehow.

[IkeDoe]

The only cases of overlapping I remember either

a) don't imply re-rolls (overlapping bonuses to AC, i.e.)
b) have a paragraph or special rule explaining the way it overlaps

I would say 1 (only the higher apply)

Btw (not related), the shield/armor SR special ability is absurd given its high price and low SR value.

Edit: Ninja'd!! }:(