RichTextBox save content as rtf is it a bug?

Hello guys

I have a problem to use RichTextBox

we use a RichTextBox, its direction is rtf and we write to it some multilevel list like

1.aaa

2.bbb

      1.aaa

       2.bbb

after save text of RichTextBox as Rtf format and reload this rtf text(or open it in MSWord)it destroys list format and spaceing of text, in new format it shows it likes

1.aaa

2.bbb

1.    aaa

2.     bbb

I test it in different situation: if Direction will be LTR it works fine

If load  destroyed text in RichTextBox and save it again it save destroyed text in true format

It seems destroyed format text has 2 more character that destroys text.

Is it a bug?

Thanks for any help or Idea