Do I need to cancel my non-B visa extension if I'm leaving Thailand for two years but plan to return later?

My non- B extension expires on 11th October. I told Immigration that I will be finishing work and flying back to Australia on that day , before coming back in 2 years to resume work at the same school. At first, when I told them that I understood the need to cancel the extension, they agreed. When I returned this morning with a letter from the school, I saw a different officer. She said it wasn't necessary and I could just go. Does this concur with your understanding of the "system". I don't want any problems should I return for a visa exempt visit in the interim, for example.