The reactor works like a wheel of Chance. It is therefore possible to win twice the same Mutant. Also, the strongest and rarest mutants (on the right) are obviously harder to get.
If there wasn't this probability then it would just be a shop. Unfortunately as this feature is based on odds, we cannot guarantee how many tries you will need to get the mutant you want.
Also, as every game based on odds you will encounter bad cycles but will also necessarily encounter winning streaks, so don’t despair!
It is frustrating to obtain same cards for over two weeks, even while shopping, this is not the way you treat one of your consistence player , do not push me to quit