I would like to breastfeed baby for at least two years. Safe to consume prenatals during these two years? Or will a regular multivitamin do same job?

Yes. There is nothing magical about prenatal vitamins. They are a way of assuring that women with rotten diets get enough vitamins for a healthy pregnancy. If you know how to eat in a healthful manner any multivitamin with minerals will be just fine. You can get all the selenium you need by eating a few Brazil nuts.