Hi there,
You can use "When an item is created or modified" and point it at the library / folder that the Excel file is in, and then every time it's modified, copy to ... the other folder you mentioned. Are these files kept on their own in a specific folder, or are they with other files? If the latter, you'll just need a trigger condition to only kick it off if it's on file X or Y.
Let me know the deets and we'll figure it out.