Watermarking Tool / Plug in on moodle?

Hello all

Bit of a shot in the dark, but I hope someone can help!

I know that a number of universities use online submission software to generate a watermarked pdf version of student assignments which students can then print and hand in separately (as a safeguard to ensure that hard copies are identical to the soft copies submitted).  Does anyone know of a moodle plug-in which could do the same, or indeed any such software that we might have access to at QMUL?

Many thanks

Mark