Join distinctly with non-unique key

[kate1]

Let's say I have the following table parts (of two much larger tables)...

CreditTable:

Project	Contract Date	Value	Line	Position
396	2/17/21	54	52	0
396	3/15/21	78	44	1
396	3/15/21	78	44	3
...	...	...	...	...

OrderTable:

Project	Contract Date	Value	Line	Position
396	2/17/21	54	30	4
396	3/15/21	78	22	1
396	3/15/21	78	22	2
...	...	...	...	...

I need to match a credit to an order by Project, Contract Date, and Value. I need it to be a one-to-one matching. When I run my current script...

JoinedTable:

LOAD DISTINCT

Project&ContractDate&Value   AS CreditKey

Project&'-'&Line&'-'&Position  AS OrderNumber

RESIDENT OrderTable;

LEFT JOIN LOAD

Project&ContractDate&Value   AS CreditKey

Project&'-'&Line&'-'&Position  AS CreditNumber

RESIDENT CreditTable;

I get something like this...

CreditKey	OrderNumber	CreditNumber
39602172154	396-30-4	396-52-0
39603152178	396-22-1	396-44-1
39603152178	396-22-2	396-44-1

But I WANT this...

CreditKey	OrderNumber	CreditNumber
39602172154	396-30-4	396-52-0
39603152178	396-22-1	396-44-1
39603152178	396-22-2	396-44-3

Is there a way to do this kind of one-to-one mapping?