If the same logic is needed for both instances the conditions should be combined.

[source,abap,diff-id=1,diff-type=compliant]
----
IF (a >= 0 AND a < 10) OR (a >= 20 AND a < 50).
  doFirst.
  doTheThing.
ELSEIF a >= 10 AND a < 20.
  doTheOtherThing.
ENDIF.
----

[source,abap,diff-id=2,diff-type=compliant]
----
CASE i.
  WHEN 1 OR 3.
    doFirst.
    doSomething.
  WHEN 2.
    doSomethingDifferent.
  WHEN OTHERS.
    doTheRest.
ENDCASE.
----