Aaron Marino of alpha m. discusses vitamins and whether or not they can build up to toxic levels. In most cases, you cannot take too many vitamins because your body is not able to absorb of all the vitamins.
If you are taking a two pills, take one in the morning and one at night to increase absorption. Be careful with the fat solubles since they are stored in your fatty tissues: A, D, E, and K. Stick to the recommended dosage with these vitamins.