I have found both a Getting Started Guide here:
and a User Manual (more comprehensive) here:
I've also looked through them and there is no mention of duplex printing capability, nor does the paper path shown in the manual show it as possible. The only way to double-sided printing is therefore manually. To do this
Print the odd numbered pages of the document (in properties box).
Remove the paper from the outlet and turn it over .
Replace it in the paper feed tray with the blank side facing you.
Print the even numbered pages of the document.
Please be careful to make sure that page 2 prints on the other side of page 1 and so on through the document, as it is very easy to put the one side printed pages in the feed tray with the last page, in the position to be printed first causing a complete waste of paper. Also leave the one side printed paper for a few minutes before refeeding as doing this too quickly can result in a paper jam.
Hope this is helpful, if so would you please register that with Fixya