Improved Defenses and Superior Feats

I was thinking about getting Improved Defenses but it shouldn't stack with the Superior (Fort, Ref, Will) Feats, which I am eventually planning to get all 3 of. They are all giving Feat Bonuses.

When I added it in the Character Builder it stacks. However, based on the rules it seems like an error.

Opinions?

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Improved Defenses
Benefit: You gain a +1 feat bonus to Fortitude, Reflex, and Will. This bonus increases to +2 at 11th level and +3 at 21st level.
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Superior Fortitude
Prerequisite: Strength 15 or Constitution 15
Benefit: You gain a +2 feat bonus to Fortitude. This bonus increases to +3 at 11th level and +4 at 21st level.
You also gain resist 3 to ongoing damage. This resistance increases to 6 at 11th level and 9 at 21st level.
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Superior Reflexes
Prerequisite: Dexterity 15 or Intelligence 15
Benefit: You gain a +2 feat bonus to Reflex. This bonus increases to +3 at 11th level and +4 at 21st level.
You also gain combat advantage against all enemies during your first turn in an encounter.
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Superior Will
Prerequisite: Wisdom 15 or Charisma 15
Benefit: You gain a +2 feat bonus to Will. This bonus increases to +3 at 11th level and +4 at 21st level.
In addition, if you are dazed or stunned, you can make a saving throw at the start of your turn to end that effect, even if the effect doesn’t normally end on a save.

A bit late...

I tried it in the character builder and they don't stack.

I tried at level 16...
With Superior (Will) I get the +3 to Will

When I select Improved Defenses, my Fort and Ref go up by +2, but no change to Will.

The feats/Character Builder seems to be working as expected.

regardless of if it works in the character builder or not, the bonuses are "Feat" bonuses and do not stack.