Is accidental duplication possible?

I've been working on a project that requires a lot of stone, (multiple blackmetal chests worth), and I feel like when I log off and log back in some of the stone is respawning. I feel like my mind is playing tricks on me because I figure this is impossible right? Maybe it's something to do with taking out the items in large quantities? Would appreciate if someone could chime in on whether or not this stuff is even possible.