Exchange currency in price condition

I have a problem as following 2 cases,the question is

A. Why system doesn't take the same exchange rule , EUR->USD or USD->EUR

B. It's possible to make it using the same exchange rule

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Order type : ZORE (Intercompany Order)

Company A

Customer currency (VD01) : EUR

Material currency (VK11) : USD

Local currency : USD

Exchange rule : 1 EUR = 1.28 USD

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Order type : ORE (Export Order)

Company B

Customer currency (VD01) : EUR

Material currency (VK11) : USD

Local currency : TWD

Exchange rule : 1 USD = 0.71428 EUR