Why does Marketo categorize different uploaded PDF files as different Types?

[Anonymous]

Marketo categorized the Type of some of our uploaded PDF files as "application/pdf" and some as "application/octet-stream".  In a Discussion post today, their PDF file was categorized as "application/download".  Then sometimes when you try to replace the original PDF file with an updated PDF file Marketo categorizes the replacement PDF file as a different type and the "Failed replace of file" error dialog is displayed. 

What causes Marketo to classify PDF files as different Types?

[Edward_Masson]

Yes!
I noticed this and is painful

[Anonymous]

Hey Marketo - please respond to this question, so we can better understand how to resolve it when it occurs.