Resolving Duplicate User IDs When Tracking Unique Subscribers in Mixpanel

Hi folks! I have a question about user identification. We are using mixpanel on frontend for almost 4 years. We have a b2b application for accountants. They can have one subscription with multiple users. We were setting User Hashes as a distinct id. But after a couple of months we decided that we do not care how many users they have anoymore. We are trying to track only subscriptions. So that we are setting distinctId our subscribers UserId from by using mixpanel API. When I want to identify how many unique subscribers using a functionality I can get a list from Users menu by filtering Users with profile and related event. After downloading event when I check the UserId column still there exist dublicates. Why? How can I resolve it?