You can use the same account to login ↗ to the Merchant Administration Portal (MAP) at once. However, simultaneous logins are limited to three person.
If there is a fourth person who wants to login, then that person must wait for one of the three people to logout first, then wait for 15 minutes. After that, the fourth person can log in.
In addition, if you do the login-logout process more than three times within 15 minutes, then this is not possible. You can login again after 15 minutes.