How many different(but overlapping) master degree can one have? Take an example, if I have a master in mathematical physics, can I have master of physics or master in mathematics?
To make the the question more applicable to other, the question is, how many different master one could have, with the contents of the degree highly overlapping?
(Another example is master in information engineering and master of information science, etc)
There are no regulations preventing you from having as many as you like. But admissions committees will use the fact that you have a related degree and possibly downgrade the application so that the slot can be given to someone else. That isn't guaranteed, of course.
But at a certain point one wonders why you would want to do this. Lifelong perpetual students aren't looked at especially favorably. Especially when institutions are government funded to some extent.
And, if you want to continue your education, why not consider a doctorate in a related field instead. There is little benefit (some) if your CV shows multiple masters.
An exception might be if you were interested in industry and one of the masters program was very narrow and applied to the industry sector you want to work in.