Random access to foreign account

So i installed MEmu the other day, installed swgoh from the playstore and started it.. Right from the begining i wasn't signed in with my google play account but with an random account of another person. I wrote him a message to make him aware of this problem.. But honestly, how can things like that happen? It was like the game thought my emulator was his device.. but even after trying stuff out like random Mac-Adress, other network settings or other device type it still gave me access to his account with new instances of MEmu.
In a game where so many big spenders exist.. it frightens me that random people could get access to my account and can mess with it...