Let's say you want to break down a message, for simplicity it is just a bit $0$ or $1$, $m$ into two messages $(m_1, m_2)$ as follows:
If $m =0$, then $(m_1, m_2) = (0, 0)$ with probability $1/2$ and $(m_1, m_2) = (1,1)$ with probability $1/2$. Similarly, if $m=1$, then $(m_1, m_2) = (0,1)$ or $(1,0)$ each with probability $1/2$.
It's clear how the message can be retrieved from the two messages, and that nothing can be know from a single daughter message (each will be 0 or 1 with equal probability regardless of the mother message), unless the random number generator has a bias of sorts.
What is this system called?
(I don't do cryptography by trade, don't know which tags to use.)