When I register as admin and developer and I try to log in as admin in one tab and after that as developer in another tab (I changed password from default one for both users) I am unable to do so since error is thrown.

I can not log in as admin twice (I log in as admin in one tab and I log in as admin in another tab while I am still logged in in the first tab)

First of all, being able to be logged in for multilple users seems to be crucial. Secondly, when I try to log in for the second time while I am already logged in, I would expect appropriate error message to be displayed to me or I would be automatically redirected to application itself when credentials have not expired yet.