The weighing range of a balance is divided. It starts with a fine range that has more precision (d1). When this fine range is exceeded, the reading automatically moves to the next range (d2) which is usually a lower step (2 x d1).
Balances of two ranges can have a defined fine range, or the fine range can be scrolled through the full range.
For example, in a model of balance of 2Kg capacity in whose first 300g the sensitivity is 0.01g. When it exceeds 300g, the sensitivity of the balance automatically changes to 0.1g. Now suppose that we put a container of 500g on the plate, tare and then add weight. If the fine range can travel through the entire capacity of the balance the reading will have a sensitivity of 0.01g. Otherwise, it would be 0.1g.