Yeah with dead pixels Apple has an 'acceptable threshold.'
Technically, they don't have to replace any screen with fewer dead pixels than that threshold.
They'll usually do it once, but not twice.
If the 2nd one is still not up to your standards (I'd be mad, too) then you can return it to Apple for a refund and then buy another one.
They won't refuse your money, but they will refuse to replace it too many times.
Good luck
Technically, they don't have to replace any screen with fewer dead pixels than that threshold.
They'll usually do it once, but not twice.
If the 2nd one is still not up to your standards (I'd be mad, too) then you can return it to Apple for a refund and then buy another one.
They won't refuse your money, but they will refuse to replace it too many times.
Good luck