Why .tmp after add Reduce File Size to an Action Wizard

Hi,

I added "Reduce File Size" to an action wizard and now all my saved files show up as .tmp files?

Why?

File named "021.pdf" now shows up as "A9R1B0.tmp.pdf"

How can I prevent this?

I am using Adobe Acrobat Pro X 10.1.16 on Windows 7.