Sort Duplicates in Dataset

Use XSUM parameter in Sort

Syntax for XSUM - SUM FIELDS=NONE,XSUM in the Sort card, and a DDNAME SORTXSUM to define the file for XSUM.

//DDName EXEC PGM=SORT
//SORTIN DD DSN=XXXXXXXXXXXXXXXXX,
// DISP=SHR
//SORTOUT DD DSN=XXXXXXXXXXXXXXXXXXXX,
// DISP=(NEW,CATLG,DELETE),
// UNIT=XXXXX,SPACE=(XXX,(XX,XX),XXXX),
// DCB=(*.SORTIN) Output file created using properties from input file.
//SORTXSUM DD DSN=&HILVL..EFS.HV01BG17.SORTED.DUP,
// DISP=(NEW,CATLG,DELETE),
// UNIT=XXXXX,SPACE=(XXX,(XX,XX),XXXX),
// DCB=(*.SORTIN) Output file created using properties from input file.
//SORTWK01 DD UNIT=XXXXX,SPACE=(XXX,(X,X))
//SYSOUT DD SYSOUT=*
//SYSIN DD *
SORT FIELDS=(1,7,CH,A)
SUM FIELDS=NONE,XSUM

Also you can refer the below link to know more details about sort :
http://itechp2pexchange.com/node/106

by using soft utility we can copy the duplicate regards of one file to another file.

Code
  //SYSIN DD *
      SORT FIELDS=COPY
      SUM FIELDS=NONE,XSUM
 //SORTXSUM DD DSN=OZA040.PC.DUP.FILE,DISP=OLD
/*