Save bug when crop sprite

version 1.2.11
Hallo! I want to slice sprite in aseprite. I choose selection using marquee tool, and them crop, ‘save as’ png. I gave a sliced png. But when I undo crop operation and then ‘save’, aseprite automatically cover the sliced file.This sprite had aseprite file already, so look like ‘save’ don’t save aseprite file.