The moment you will use WhatsApp on the phone - you will have to re-register on Miranda and vice versa.
But I never used Whatsapp on phone, only in Miranda. I registered it (pressed "request code" in plugin and entered the numbers sent by SMS to my phone number). But after some days it just stopped working for no reason (the only reason I could really think of was the IP address cause nothing else was changed). Now I'ver re-requested the code (in miranda) and registered again with the same number and Whatsapp is working again (in Miranda). But that's strange.
I use Miranda only on one device (my PC), not on phone, tab or anything else. Also I was using whatsapp in Miranda for over a month or so and there wasn' such an issue..