Injectable H1N1 and seasonal flu can be give together as they are killed viruses and manufactured the same with different antigens. However, the live virus FluMist version of each vaccine cannot be given together as we have come to understand in the medical community.
Wayne Yankus, MD, FAAP
expert panelist: pediatrics
Your doctor is the one who can give the best answer to this question, as he or she will know if there are any other factors to be considered in the decision.
As to what the US Centers for Disease Control has to say on it, on the "H1N1 Flu | Questions and Answers" page on cdc.gov (link below) there is a related question and answer, copy/pasted here:
Can the seasonal vaccine and the 2009 H1N1 vaccine be given at the same time?
It is anticipated that seasonal flu and 2009 H1N1 vaccines may be administered on the same day. However, we expect the seasonal vaccine to be available earlier than the H1N1 vaccine. The usual seasonal influenza viruses are still expected to cause illness this fall and winter. Individuals are encouraged to get their seasonal flu vaccine as soon as it is available.