Split.train.test got a Join columns must be unique error in win 10 but working at win 7

My guess would be that when switching to Win 10, you also installed the latest version of R and dplyr, whereas the Win 7 installation might not have been fully up to date, and that a specific operation in your code is no longer possible.

So it will help to provide a reprex, in particular providing (part of) the code of Split.train.test() and what fraud_latest looks like.