If evaporated milk is mixed with water, does it have the same calcium and vitamin D amounts as regular milk?
If 100g of evaporated milk contains 250 mg of calcium and milk 120mg then yes, adding 100g of water and then using half of liquid yeld the same amount of calcium.

But, depending on the brand and region ecaporated milk usually contains added vitamin D so  one could assume that even diluted the Vit D content would be higher than in regular milk.