Is it a Good Practice to put Battery(1.5Volts) with Opposite Polarity
No, you should not do that because instead of prolonging the life of the battery, it will even make it shorter because it is inserted in opposite polarities. It might also make the battery hot and a tendency to explode in rare cases. If this happens, it can damage your device.
Inserting the battery in opposite polarities may also have the tendency to make the battery leak. If you want to prolong the life of the battery of your wireless mouse when it is not in use, try removing the battery. This way, you are sure that nothing is consuming the battery.
Before, we used to do that on flashlights inserting the battery in opposite polarities when not in use. But instead of preserving the battery’s life, it even made it weaker the next time we used it. So, it is really not good to do that on any types of batteries.