I'm trying to print double side pages with my laser printer, I noticed that when I run my paper 2 times in the printer, the paper becomes kinda grey and not as white as it was... I read online that when the toner is fused on paper the temperature in the fuser assembly is about 427 °C, could it be that reason or my drum is damaged?
I also tried to print dots in one single paper 10 times just to see the results and it became darker the more I print on it.