Doing two PhDs one from Electrical Engineering and other from Theoretical Physics I am currently doing MPhil degree in Electrical Engineering (Sensors &amp; Robotics). I did my bachelor degree in Electrical Engineering as well.

I have real motivation and love to do research on Theoretical Physics as well. The more I learn physics more I need to do a research on physics.

My initial thought was to get an M.Phil on the current University in EE and get my Ph.D. in Electrical Engineering from some other more reputed university. But since now I have an idea of doing Ph.D. in physics, now I am thinking of extending my M.Phil to a Ph.D. and finish it and do another Ph.D. on physics in a foreign University (Australia).

I have two questions,
1)what is your opinion on this path? I appreciate answers, especially by PhD supervisors.
2) Does getting a Ph.D. in electrical engineering minimize my chances of getting selected for a PhD( funded Ph.D.) in theoretical physics? (I mean is it better to apply for Ph.D. in theoretical physics after completion of just M.Phil). 
Note: It takes only one extra year for Ph.D. if I extend my M.Phil.
If your aim is to do a PhD in theoretical physics (TP), then you should attempt to get on a corresponding PhD programme straight after your MPhil.

However, this may not be so easy, depending on the suitability of your current qualifications and qualities to TP research (and to the openness of potential supervisors to applicants from EE). So, failing to secure a PhD in TP, you can attempt to secure a PhD in EE (though in practice you may need to apply to both options simultaneously).

I don't think that obtaining a PhD in EE diminishes your chances for a PhD in TP, on the contrary. However, after a PhD in EE, you may very well change your mind and go for a career in EE. You should definitely allow for that option at the outset, i.e. choose the University for any PhD with care: don't just consider a PhD in EE as a step towards TP or a stop gap.