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Welcome to ITKE. It's not clear what problem you are having.
Are you asking us to write a complete program for you (for free) and you aren't telling us anything about the file? Do you have a definition of "duplicate"? Are entire rows duplicated or are there simply duplicate keys that need to be resolved? Your question title refers to "duplicate members"; is that a reference to a multi-member file that has some members with data the same as some unknown number of other members? If some rows (or some members) are removed, are there criteria to determine which one is not removed?
It's almost guaranteed not to do you any good, but here's an example of a RPG program that removes duplicates:
exec sql CREATE TABLE MYLIB/NONDUPE as
(SELECT DISTINCT * FROM MYLIB/DUPES) WITH DATA ;
exec sql DELETE FROM MYLIB/DUPES ;
exec sql INSERT INTO MYLIB/DUPES SELECT * FROM MYLIB/NONDUPE ;
*INLR = *ON ;
I don't see how that could help you, though. Much more information is needed to make such a program useful, and it's probably not a good way to do the work.