Harvard referencing: same year, same last name, same initials
The guidelines to the venue you are submitting to must be your guideline. After all, the title of the paper is what distinguishes one author from the other. And this information is present in the bibliography.

For the in text references, neither University of Leeds nor The University of Melbourne has any suggestion for such situation. However, both use the style (Smith, 2012a) and (Smith, 2012b) for same author, different publications. So, that is not correct.

Personally, I would go with adding a footnote at every page that the citation occurs, maybe with a Google Scholar or personal website page. 
Writing the full name would not be a generic solution as there might be two different authors with same name and same surname.