Having more than one tray of ice makers in a fridge serves the purpose of providing a larger ice-making capacity. When a fridge has multiple ice maker trays, it can produce a greater volume of ice, which is especially useful for households or settings where ice usage is high, such as parties or large gatherings. The additional ice maker trays ensure that there is a steady supply of ice available, reducing the risk of running out during peak usage.
As for the second part of your question, it is not normal for a typical refrigerator to refill itself while you're away. The ice-making process in most refrigerators is not automatic in that sense. Ice is produced by the fridge's ice maker, which is connected to a water supply. When the ice is used or melts, the ice maker senses the need for more ice and starts the freezing process again, drawing water from the connected water supply line.
However, if you have a more advanced refrigerator with features like a built-in water dispenser or an ice maker with a storage bin, it might seem like the fridge is "refilling itself" while you're away. This is because these refrigerators often have larger ice-making capacities and can store a significant amount of ice in their bins, ready for use even when the ice maker is not actively producing more ice.
In such cases, the fridge doesn't actually "refill" itself, but it can store a reserve of ice that was made earlier, providing a constant supply even if you're not using the ice maker in real-time. Some advanced fridges with smart features might also have the ability to monitor and adjust ice production based on usage patterns, but this is not the norm for most standard refrigerators. Always refer to your refrigerator's user manual to understand its specific ice-making capabilities and features.