Appreciate that applying or popping a Git stash just alters the working directory and/or stage. It does not make a new commit. Therefore, simply doing a hard reset should get you back to where you were before the first stash:
# from your branch
git reset --hard
That being said, if you wanted to retain some permutation of the changes since the first stash, that is another story and would require more work and thought to pull off.
Note: Generally speaking, popping a Git stash is risky, because if something goes wrong along the way, you can't reapply the same stash as it has already been popped from the stack. Use git stash apply
for best results.