Hello ..
We can achieve this by using control break statements.
Assume your internal table IT_TAB has your values and try as below,
sort it_tab by field1 field2.
LOOP AT it_tab INTO wa_tab.
AT NEW field1.
WRITE wa_tab-field1.
ENDAT.
WRITE 20 wa_tab-field2.
skip.
ENDLOOP.
Regards,
Arun