Safe yeah maybe, but you don't want to be interfering with MP though while it's working on your account. MP does not use API-s, it emulates manual browser actions, therefore it opens a browser and performs each FB action as you would normally when operating manually on a PC. And of course, this kind of activity you are doing is suspicious as fuck, because there is no way for a normal person to do multiple actions at the same time from 2 different locations, so this is a sure way to tell FB that you are botting. Never really tested this to be honest (except with my main personal account when I use it and my gf also uses it at the same time for the farmville shit she sends to her account), but it's common sense.