Even when using the same randomseed in Lua, get different results?

I have a large, rather complicated procedural content generation lua project. One thing I want to be able to do, for debugging purposes, is use a random seed so that I can re-run the system & get the same results.

To the end, I print out the seed at the start of a run. The problem is, I still get completely different results each time I run it. Assuming the seed doesn't change anywhere else, this shouldn't be possible, right?

My question is, what other ways are there to influence the output of lua's math.random()? I've searched through all the code in the project, and there's only one place where I call math.randomseed(), and I do that before I do anything else. I don't use the time or date for any calculations, so that wouldn't be influencing the results... What else could I be missing?