B

When a ball is thrown at different angles but with the same speed and from the same point, the range remains the same. The heights attained at these angles are given by the equations for projectile motion. The maximum height for an angle \theta is given by \( y = \frac{u^2 \sin^2 \theta}{2g} \). For two angles that provide the same range but different heights, the relationship between their heights can be derived from the symmetry of projectile motion which gives us that the sum of heights for two complementary angles (e.g., \theta and 90 - \theta) that achieve the same range is equal to the maximum height achievable with that speed. Hence, \( y_1 + y_2 = \frac{u^2}{g} \).
Therefore, the correct option is B: \( \frac{2u^2}{g} \).