When you select duplex mode, the document will print on one side and then stop before fully ejecting the page. It will pause a few seconds to dry then withdraw the page back into the printer and flip it around. Then it will began to print on the other side of the paper.
Is it possible to change the default pause ?
When printing on the other side, the ink is not fully dry and the document is stained.
You can change it when using the windows canon driver...