Something similar happened to me in 2017, I got $500K (abt 2.6cr) credit for my year end bonus instead of 500K INR. I reported that to the HR the same day and even told the bank about it ( They called me first as it was a flagged transaction). The company asked me to transfer the money back to their account – It took me a month to reverse the transaction as I had to visit the bank multiple times ( I kept the 80K interest on it :))
This was just after demonetisation as well as there were too many news articles about people moving money to random accounts to avoid scrutiny. I asked HR to issue me a official letter stating this was done as a mistake and it has been reversed successfully.
Please make sure you ask for the official letter to keep yourself safe from any IT scrutiny later as well.