set_skill_lvl does not work

[jonpro142]

Using set skill lvl or set elo rating seems to have no effect for me. (and prlly also the set depth)

what i did:
i created 2 instances. stockfish1 and stockfish2
one of them i gave a elo rating of 100, the other one got one of 2000. Afterwards i let them play some games.
suprisingly both win like half of the games.
same thing happend if i set the skill level or depth instead.

afterwards i used the chess library with chess.engine to check it a bit (just a few test runs).
against stockfish (through chess.engine with .1 second limit) lvl 1: the stockfish library wins
against lvl 20 it looses all
against lvl 4 this stockfish library won like 70%