Yes, as part of the upload process, MX analyses the data, producing a MD5 checksum value. This is compared with the uploaded file to ensure that the data is complete. 

Although the data will expire, that checksum is retained and there are several tools which allow you to obtain the checksum value of the data that still sits on your local machine or corporate network. If the values are the same, there is a high probability that those files are the same.

This information is not displayed to the end user, so if you require this info, please contact the MX team in the chat tool.