You may want to modify a file but also preserve the original version. In this case, you can create a copy of the file from both the Canvas and Gallery:
From Your Canvas:
In the top toolbar, click File > Make a Copy.
Click View Copy to go to the new version or Stay here to continue working on the original file.
A copy of the file will appear in your Gallery.
From Your Gallery:
Find the file you’re looking for, then click the three dots on the right-hand side.
Click Make a copy.
A copy will be added to your Gallery.