[Duplicate] Mixed Attributes ON - Quantity Discounts - not calculating correctly

[DogTags]

ZC 138a
Fresh Install, Demo store
No addons
Totally uncustomized
Prob started right after install
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1. Did fresh install of zc138a and enabled the demo store

2. Added an item called Widget 1:

Price: $100.00
Weight: 1 pound

3. Added Color Attribute from native selections: 9 colors, black default, no pricing features for attributes

4. Added 5 Quantity Discount boxes:

2:$90
4:$80
6:$70
8:$60
10:$50

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5. Added "Widget 1" to shopping cart:

1 Black
2 Blue
4 Brown

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6. With "Discount Qty Applies to Mixed Attributes" OFF, shopping cart shows:

1 Black - $100.00 ($100.00 each)
2 Blue - $180.00 ($90.00 each)
4 Brown - $320.00 ($80.00 each)

All above is correct

7. However, with "Discount Qty Applies to Mixed Attributes" ON, shopping cart shows:

1 Black - $70.00 ($70.00 each)
2 Blue - $160.00 ($80.00 each)
4 Brown - $$280.00 ($70.00 each)

See the "2 Blue - $160.00 ($80.00 each)" ?

Rather, that should be:

2 Blue - $140.00 ($70.00 each) with Discount Qty Applies to Mixed Attributes ON (if I understand things correctly)