Attached Files
To refer to attachments on a page, use attachment:filename, as shown below in the list of files. Do NOT use the URL of the [get] link, since this is subject to change and can break easily.
New Attachment
An upload will never overwrite an existing file. If there is a name conflict, you have to rename the file that you want to upload. Otherwise, if "Rename to" is left blank, the original filename will be used.