When using two or more accounts at the same time on a same browser, it is highly likely that there will be problems with data integrity while using Zervant.
This is related to browser cache and account data that is stored there in the duration of your login session.
Things that may happen are invoices or customers being saved in the wrong account or wrong data displayed in different app views. These issues are not Zervant-specific and same type of behaviour can occur while using any web app while you're logged in with two or more accounts at the same time.
If more accounts have to be used, the best way is to use different browsers for different accounts (e.g. Google Chrome for account 1 and Mozilla Firefox for account 2).