Program run speed (loops per second) is too fast for random number generation?

I'm trying simply trying to give randomly generated vaules to certain variables, if I slow down the program, the numbers are generated, what seems like random, but if I let the program go, I can restartedly see same ones being generated or used, not sure.

I don't really know which code part to post, but:

struct RANDOM, template <typename ITEM> struct LIST, _generate() https://pastebin.com/ZDktF4jQ

I read somewhere about millisecond exacts, which I would guess could have an effect for duplicates appearing or same ones generated?

Any help appreciated.