[mikeyla85]

This.

If it doesn't operate like Dropbox under the hood, don't make it look like Dropbox in your interface.

If an action creates a copy of objects, call it "Copy Objects" or whatever.

I think that presenting an S3 bucket as a set of files that you can select and perform operations on sets up false expectations here. And not showing incomplete multipart uploads in the file listing or having any way to see they are there isn't great.