It’s already been fixed so you shouldn’t be able to go above your target rank anymore.
The rank rewards weren’t calculated properly on the end of the game in last season.
If it’s still possible then I’d like to have someone in the top 100 create proof of this by creating a new account and getting above the position of their main account while their main account continues to use bonus too daily.
Either way, it’s nearly impossible for us to know for sure people have 2 accounts.
There are ways to detect and prevent stuff but people can always work around it.