It appears you want only one record with each key and for that record you want the sum of the two fields. If so, you can use a DFSORT job like the following:
//S1 EXEC PGM=ICEMAN
//SYSOUT DD SYSOUT=*
//SORTIN DD *
DENIS0000500010
DENIS0000500010
MARCO0000500012
MARCO0000500012
//SORTOUT DD SYSOUT=*
//SYSIN DD *
OPTION ZDPRINT
SORT FIELDS=(1,5,CH,A)
SUM FIELDS=NONE
OUTREC BUILD=(1,5,6:6,5,ZD,ADD,11,5,ZD,TO=ZD,LENGTH=5)
/*
If you're not familiar with DFSORT and DFSORT's ICETOOL, I'd suggest reading through "z/OS DFSORT: Getting Started". It's an excellent tutorial, with lots of examples, that will show you how to use DFSORT, DFSORT's ICETOOL and DFSORT Symbols. You can access it online, along with all of the other DFSORT books, from:
www.ibm.com/servers/storage/support/sof ... tmpub.html