how

How is it possible having two bottles of sealed water but they each
have different level of water? These bottles are supplied by the
hotel for the SPG guests for room use. There were condensation inside
the bottle so I would imagine something is being evaporated from
inside. Though insignificant. How then we have two different level
from the same batch of water from factory?

Three explanations? 1) Evaporation was faster from one bottle to
another due to the different temperature between the two? 2) Manual
water filling station at factory? 3) Re-calibration of water filling
mechanism? Or 4) If we don't get sick from it, it's ok.