For a surjective function from A--> B, I was just wondering if more than one elements in B can point to the same element in A if the function is surjective.
The object you are describing is not a function. A function from A into B is a set of ordered pairs (a, b) such that a is in A and b is in B and whenever (a, b) and (a, c) are elements of the function, we have b = c. In other words, as a function from R into itself, it does not pass the vertical line test.