That's an interesting observation Irishgirl. I take depakote as a mood stabilizer, and abilify which is an anti-depressant; but I take that medicine as it is also an anti-psychotic.( I suffered a psychosis in the past). Furthermore, my psychiatrist isn't anxious about the idea of my trying lamictal for whatever reason. He said that he would not consider treating me with that drug unless I was unwell with as much as 30mg of abilify (I now just take 10mg).
So I guess that everyone is unique, and doctors treat patient's differently based on their histories and success rates with various combinations of drugs. I would try what your dr. suggests for a few weeks; and if it doesn't work, then you will know yourself, as you are the consumer of the drugs.