This may occur when you upload a file with an '&' in the filename. The '&' symbol is a special character in oracle, and using it in the file can cause issues with the process. If a file with '&' in it is uploaded alone, or is the first file uploaded by the Interaction Upload in a series of files, then TA will report an error with the process and not upload the file at all. However, if the file with an '&' in it is uploaded after another file has already been uploaded in the same Upload Interactions job, then TA will NOT report an error, but will fail to load the file and end up adding the same set of interactions from the previous file again.
Solution is to not use the character '&' in filenames. Any Interaction Uploads that loaded the same file twice should have the process id for the duplicate load undone with the Undo Upload/Download Procedure to remove the duplicate interactions.
Here is a list of special characters that should not be used in file names: