[fpc-pascal] TStringList.Put calls change even if value hasn't changed

[Bart]

When you do something like
  StringList1.Strings[Index] := Value
it calls TStringList.Put().

I would expect that if Value = Strings[Index] then nothing happens,
and no Change or Changing are called.

Muttatis mutandis for PutObject.

Procedure TStringList.Put(Index: Integer; const S: string);

begin
  If Sorted then
    Error(SSortedListError,0);
  If (Index<0) or (INdex>=Fcount)  then
    Error (SListIndexError,Index);

//First check for   Flist^[Index].FString = S, and if so exit?

  Changing;
  Flist^[Index].FString:=S;
  Changed;
end;



Procedure TStringList.PutObject(Index: Integer; AObject: TObject);

begin
  If (Index<0) or (INdex>=Fcount)  then
    Error (SListIndexError,Index);

//First check for Flist^[Index].FObject equals AObject, and if so Exit?

  Changing;
  Flist^[Index].FObject:=AObject;
  Changed;
end;

Of course I might be horribly wrong.
Can someone elaborate on this?

Bart