Well, you can't have the same filename on two files in the same directory, so I'm going to guess that there are multiple directories in question. If this isn't the case, you have one odd Unix system. Last time I saw multiple files with the same name, I was working with a VAX cluster.
If you know all of the directory names in advance, you can use the "cd" command in FTP to navigate around and the "ls -l" or "dir" command to check file dates. If you don't know the directory names, you have a piece of work to do a "dir" in the root directory, extract the names of all subdirectories and the dates of all files with that name, and recurse.
By any chance, is the file "date" part of the actual name? Like "useful.data.20101211" and "useful.data.20101214"?