Another way of getting the desired results is to simply concatenate both files to sortin as they have same DCB properties and validate the indicator
//STEP0100 EXEC PGM=SORT
//SYSOUT DD SYSOUT=*
//SORTIN DD DISP=SHR,DSN=Your Input FB 200 Byte file1
// DD DISP=SHR,DSN=Your Input FB 200 Byte file2
//SORTOUT DD SYSOUT=*
//SYSIN DD *
INREC IFTHEN=(WHEN=(1,1,CH,EQ,C'H'),OVERLAY=(201:8,4)),
IFTHEN=(WHEN=NONE,OVERLAY=(201:2,4))
SORT FIELDS=(201,4,CH,A,1,1,CH,D),EQUALS
OUTREC BUILD=(1,200)
//*