Dear- Just worry about conflicting. Is it OK to login webtrader in chrome (works fine) and additional TWS , in same machine? How about in different machine?
I think you can't use the same account on two different instances of TWS no matter if they are on the same machine or not.
I heard some broker in some country allows two or three login in one machine, if he changes setting for multiple login in advance. However, IB does NOT allow it, if yours are true.
TD Ameritrade allows login into ThinkOrSwim from multiple devices - I often have it open on my desktop and iPhone at the same time. Would be nice if IB allowed that as well..
I agree yours that it would be helpful for IB, to let them know before a customer change broker forever.
The reason probably is security. You'd want to know if your device is compromised and informing you're signed in from a different location is one method. There is also the issue of data, providers don't allow you to stream paid real-time quotes from multiple sources AFAIK.
Actually, you can log in two ways in the same account, but you have to define more than one user in account management.