Merging 02 detail tables, delete the duplicate values ​​from both sides in SQL Server 2008

In my case, both tables are details, sometimes it has 01 element in Tables A with multiple elements in Table B and vice versa.

SELECT DIFFERENT
x._PROCESS_INST_NO,
x._GOODS_CD,
x._QTY,
y._GOODS_CD,
Y._QTY
SINCE [TBL_PROC_PM] X
LEFT EXTERNAL COMBINATION (SELECT t._PROCESS_INST_NO,
t._GOODS_CD,
t._QTY
SINCE [TBL_PROC_PMS] t) and ON y._PROCESS_INST_NO = x._PROCESS_INST_NO
WHERE y._PROCESS_INST_NO IN (& # 39; 631886 & # 39 ;, & # 39; 635312 & # 39;)

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I want to eliminate duplicate values ​​from both sides. Please help. Thank you!