HtmlInputFile: mimetype of image/jpeg vs image/pjpeg?

[Guest]

I have an ASP.NET page with an HtmlInputFile control. On certain machines,
when a user uploads a jpeg image, the uploaded file has a MIME type of
image/jpeg and on others the uploaded file has a MIME type of image/pjpeg.
What could be causing this difference and how can I make it uniform?

Thanks.