In bitcoin we do not have method than we can double our bitcoin safely we always need to take a risk to earn profit but we can reduce the risk we have by investing multiple, bitcoin has more method to invest then we need to try it all to earn more profit.
Investing on multiple or single platforms wont reduce the risk unless all of them are safe, because even if you invest in one place that is quite safe you will still stay safe but even if you invest in multiple places but some of them are suspicious then it is not recommended.