Hello, 

Some time ago I bought the first copy of minecraft, after some time I bought a second copy for my sister, on the same email... Everything worked, I logged in via mojang and my sister via microsoft and we had two different profiles/account. Now, when I wanted to log in, I got an error that my account has been migrate and I cannot log in to it either on the website or in the luncher. Sister account still worked. I have purchase confirmations for both accounts if needed