Modifier Incompatibility with Group of Lines

I have modifiers setup at the "Line" level.  The discounts get applied based on the item category (e.g. Category A = 30%, Category B = 25%, etc).  This is working as expected.

Now I need to add a promotion based on Order Amount.  For example, if Order Amount Between $5000 and $10,000, 50% discount, Order Amount Greater than $10,000, then 60% discount.

I was looking to use "Group of Lines" modifier for this Order Amount based discount.  The Order Amount promotion is applied as expected.  However, I am getting both the Line and Group of Line discounts applied at the same time.  The order line should not be allowed BOTH discounts at the same time.