You can use the same lawyer with the buyer to assist you in the transaction such as submitting documents, preparing documents and presenting documents at the land office or to any other relevant authorities.
However, it is not advisable to do so as if there are any disputes, the same lawyer will not be able to act for you as that lawyer would be in a conflicted position. That lawyer is also acting in the interest of the buyer. Thus, it is advisable for you to be prudent in respect of the clauses in the agreement(s) and document(s).
Hope this helps.