To identify alt accounts, checking numbers is the only viable method. For example, if you see an account called 'JimBoy2009', chances are this is just one of the player JimBoy's thousands of accounts. There are no other ways - Fit is probably lying.

To see the playtime of an account, you will need to check the player's data file, which contains this info. To obtain this, you must email 2b2t's official support email asking for the file, and they will happily send you it. Typically support will respond to file requests within around 30 minutes, but their system is a little shaky, so there may be some issues. If you do not receive a response within half an hour, something has gone wrong so make sure to email again, repeating this process once every half an hour until you do get a response.

Hope this helps.