Vitamins A and D can build up in your system; the rest mostly wash out when you pee. You would have to gulp them down by the handful. If you just accidentally take two instead of one, that's no problem.
Long story short: yes, some vitamins can be toxic at certain levels. Sometimes toxicity can be as bad, or worse, than deficiency. Minerals also can be bad in both excess and deficiency. Water has toxic levels.