Stacking Smite Evil?

[dynilath]

Smite Evil wrote:

Smite Evil Single Action Feat 6

Champion
Prerequisites divine ally (blade); tenets of good
Your blade ally becomes an even more powerful tool against evildoers. Select one foe you can see. Until the start of your next turn, your Strikes with the weapon your blade ally inhabits against that foe deal an extra 4 good damage, increasing to 6 if you have master proficiency with this weapon.

If the foe attacks one of your allies, the duration extends to the end of that foe’s next turn. If the foe continues to attack your allies each turn, the duration continues to extend.

I was discussing on Champion build today with my friends, and one of us pointed out that the damage from Smite Evil is actually not a "bonus", it's extra damage, thus it can stack.

Then, can one Champion use Smite Evil multiple times and choose a same target, and get multiple times of extra damage on his Strike?

e.g.
1 action - Smite Evil
1 action - Smite Evil
1 action - Strike with 8 extra damage.

I have a feeling of not possible but I can't convince myself by RAW.

[Mark Seifter]

Duplicate Effects
When you’re affected by the same thing multiple times, only one instance applies, using the higher level of the effects, or the newer effect if the two are the same level. For example, if you were using mage armor and then cast it again, you’d still benefit from only one casting of that spell. Casting a spell again on the same target might get you a better duration or effect if it were cast at a higher level the second time, but otherwise doing so gives you no advantage.

(Core Rulebook 443)

[dynilath]

Mark Seifter wrote:

Duplicate Effects

When you’re affected by the same thing multiple times, only one instance applies, using the higher level of the effects, or the newer effect if the two are the same level. For example, if you were using mage armor and then cast it again, you’d still benefit from only one casting of that spell. Casting a spell again on the same target might get you a better duration or effect if it were cast at a higher level the second time, but otherwise doing so gives you no advantage.

(Core Rulebook 443)

Thank you.

Thus Smite Evil on different target at the same time is not possible either.

And it's literally on page 444.