If you win the lottery twice in a row you can be sure someone will be doing an official investigation as to whether you cheated or not. Even though you can't prove if something is truly random or not, you can be reasonably confident if you see odds that are on the order of lottery level luck. That said most of the 'bad luck' people report are nowhere close to lottery level odds, and the ones that are tends to be so improbable that there's no reason to believe they're true (usually they'd be events that's equivalent of winning 2 lotteries in a row).