Answer
$\text{Same amount of elastic potential energy will be stored in both cases.}$
Work Step by Step
$\text{For a spring performing simple harmonic motion:}$
$$ U = \frac{1}{2}kx^2$$
$\text{where U is the elastic potential energy}$
$\text{k is the spring constant}$
$\text{x is the displacement from mean position}$
$\text{Clearly even if you stretch the spring or compress the spring}$
$\text{by the same amount the elastic potential energy stored}$
$\text{will be same}$
