Using Sprite Packer doubled total memory usage ?

Hi,

Lately I figured out that I have made a mistake when importing designed images for my game UI from Photoshop to Unity. For each button image sprite I made a new image. I didn't know that I needed to use only one atlas with all the sprites inside this one. Then I understood that I needed to use Unity's sprite packer to pack all these sprites in a single pack using the same packing tag for each of the sprites i needed to pack. After doing so the draw calls were reduced just a little. And before packing the sprite the total memory usage was about 170 mb and after packing the sprite the total memory usage was doubled to approximately 300 mb. Why did this happen ? How can i solve this ?

If anyone knows how to fix this it would be nice. Also, I care for memory usage because I am developing this game for mobile devices and their memory is limited.

Thanks, Gerald.