Duplicate Values

I have two tables similar to this:

-Invoice_Table-
Customer  Job_No  Sale_Amt
12345678  123456  123.45
87654321  246800  645.23

-Vendor_Table-
Customer  Job_No  Vendor  Vendor_Cost
12345678  123456  ABCDEF  10.50
12345678  123456  UVWXYZ  20.92
87654321  246800  LMNOPQ  12.45

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And I have a query similar to the following (but a LOT more complex):

SELECT
	Inv.Customer,
	Inv.Job_No,
	Ven.Vendor,
	Ven.Cendor_Cost,
	Inv.Sale_Amt
FROM
	Invoice_Table Inv
	LEFT OUTER JOIN Vendor_Table Ven
		ON Inv.Customer = Ven.Customer
		AND Inv.Job_No = Ven.Job_No

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This query produces output similar to the following:

Customer  Job_No  Vendor  Vendor_Cost  Sale_Amt
12345678  123456  ABCDEF  10.50        123.45
12345678  123456  UVWXYZ  20.92        123.45
87654321  246800  LMNOPQ  12.45        645.23

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This is causing a problem in Crystal (where I use this) as it's adding 123.45 twice.

Is there any way that I can, using the tables provided (that I can't modify) produce results something like this:

Customer  Job_No  Vendor  Vendor_Cost  Sale_Amt
12345678  123456  ABCDEF  10.50        123.45
12345678  123456  UVWXYZ  20.92        0 (or NULL)
87654321  246800  LMNOPQ  12.45        645.23

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TIA