This will give u two column header for alv:
REPORT ZII_RKP_TEST MESSAGE-ID AA .
TYPE-POOLS: slis.
DATA:
x_fieldcat TYPE slis_fieldcat_alv,
it_fieldcat TYPE slis_t_fieldcat_alv,
l_layout TYPE slis_layout_alv,
x_events TYPE slis_alv_event,
it_events TYPE slis_t_event.
DATA:
BEGIN OF itab OCCURS 0,
vbeln LIKE vbak-vbeln,
posnr LIKE vbap-posnr,
in TYPE i,
out TYPE i,
END OF itab.
SELECT vbeln
posnr
FROM vbap
UP TO 20 ROWS
INTO TABLE itab.
x_fieldcat-fieldname = 'VBELN'.
x_fieldcat-seltext_l = 'VBELN'.
x_fieldcat-tabname = 'ITAB'.
x_fieldcat-col_pos = 1.
APPEND x_fieldcat TO it_fieldcat.
CLEAR x_fieldcat.
x_fieldcat-fieldname = 'POSNR'.
x_fieldcat-seltext_l = 'POSNR'.
x_fieldcat-tabname = 'ITAB'.
x_fieldcat-col_pos = 2.
APPEND x_fieldcat TO it_fieldcat.
CLEAR x_fieldcat.
x_fieldcat-fieldname = 'IN'.
x_fieldcat-seltext_l = 'IN'.
x_fieldcat-tabname = 'ITAB'.
x_fieldcat-col_pos = 3.
APPEND x_fieldcat TO it_fieldcat.
CLEAR x_fieldcat.
x_fieldcat-fieldname = 'OUT'.
x_fieldcat-seltext_l = 'OUT'.
x_fieldcat-tabname = 'ITAB'.
x_fieldcat-col_pos = 3.
APPEND x_fieldcat TO it_fieldcat.
CLEAR x_fieldcat.
x_events-name = slis_ev_top_of_page.
x_events-form = 'TOP_OF_PAGE'.
APPEND x_events TO it_events.
CLEAR x_events .
l_layout-no_colhead = 'X'.
CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
EXPORTING
i_callback_program = sy-repid
is_layout = l_layout
it_fieldcat = it_fieldcat
it_events = it_events
TABLES
t_outtab = itab
EXCEPTIONS
program_error = 1
OTHERS = 2.
IF sy-subrc NE 0.
MESSAGE ID sy-msgid TYPE sy-msgty NUMBER sy-msgno
WITH sy-msgv1 sy-msgv2 sy-msgv3 sy-msgv4.
ENDIF.
*&---------------------------------------------------------------------*
*& Form TOP_OF_PAGE
*&---------------------------------------------------------------------*
* text
*----------------------------------------------------------------------*
FORM top_of_page.
*-To display the headers for main list
FORMAT COLOR COL_HEADING.
WRITE: / sy-uline(103).
WRITE: / sy-vline,
(8) ' ' ,
sy-vline,
(8) ' ' ,
sy-vline,
(19) 'PATIENT'(015) CENTERED,
sy-vline.
WRITE: / sy-vline,
(8) 'VBELN'(013) ,
sy-vline,
(8) 'POSNR'(014) ,
sy-vline,
(8) 'IN'(016) ,
sy-vline,
(8) 'OUT'(017) ,
sy-vline.
FORMAT COLOR OFF.
ENDFORM.
result: 