Attachments in Issue Tracker are downloading in different formats after exporting and importing

In a Issue Tracker, I've created several issues with attachments with "exe", "png", "ppt" extensions. Once these issues have been Exported and Imported back into the repository the attachment which is being downloaded are downloaded with a different extension.

This issue can be reproduced with the steps below and as shown in the attached screenshot.

Steps

1. Create Issue
2. Attach a file with ".exe" extension
3. Create 2nd Issue and attach a file with a ".png" extension
4. Created 3rd Issue and attach a file with a ".ppt" extension
5. Download all files with correct extension
6. Export the Issues and the Import it back again (could be the same repository or a different
   repository).
7. Download the file for the latest Issues in the list , it downloads the file with the extension ".png".

Screenshot