Using FASTCOPY if the member being copied already exist in target, and the process did no expect this (no Replace specified), the step complete with an RC=0 and message FCO211W is issued.
FCO142I FASTCOPY NOT SELECTED - NO REPLACE OPTION
FCO233I NO MEMBER(S) WERE SELECTED FROM THIS DATASET
FCO211W 1 MEMBERS NOT FOUND OR NOT PROCESSED
FCO210U STORAGE 1102K ALLOC 1102K USED
FCO220U 00.00.00.11 SECS ELAPSED 00.00.00.00 TCB CPU 00.00.00.00 SRB CPU
FCO230I PDSMAN FASTCOPY PROCESSING COMPLETE 10/26/2016 15:11:14 CC=00
FASTCOPY sets the RC to 0 because IEBCOPY does, that is, FASTCOPY is doing what IEBCOPY does.
Use the following parameter, PARM=RC4NOREP on the EXEC PGM=IEBCOPY, it sets a return code of X'04' when a module is not copied from the source data set to the target data set because REPLACE was not specified.
It works for both IEBCOPY and FASTCOPY, it is a standard IEBCOPY feature, hence not documented explicitly in the PDSMAN documentation.