Hi Praneeth,
write APPEND VALUE TO LIST. logic in INITIALIZATION event.
use a flag variable, say lv_flag type abap_bool.
and change the AT SELECTION-SCREEN OUTPUT event logic as below.
if lv_flag eq abap_false.
NAME1 = 'PR_NAME1'.
CALL FUNCTION 'VRM_SET_VALUES'
EXPORTING
ID = NAME1
VALUES = LIST.
lv_flag = abap_true.
endif.
Then check the process.
Regards,
Praveer.