When a liquid solidifies in a cell that already contains a pile of debris, the now bigger pile doesn't calculate it's new temperature properly. Instead it maintains it's old temperature.
In both scenarios there was a small pile at 400C prior to the doors opening.
In the first screenshot right side, the liquid falls as the droplet animation and does not interact with anything until it lands on the metal tile. It instantly solidifies and adds to the existing pile. The pile stays at 400C even though more and more hot material is being added to it.
In the second screenshot left side, the liquid falls as a blob and solidifies before hitting the metal tile. This makes a falling debris pile which adds to the existing pile. This new pile has it's temperature calculated correctly (or at least it appears so).
Load save, flip both switches, unpause, observe temperatures of the two piles.