I just came across this sentence in my textbook:

選挙権は国民の権利でもあれば、同時に義務でもある。

I notice that the sentence use "でも" instead of simply "も." What's the difference between "でも" and "も" in this context?

Thanks in advance

選挙権は国民の権利でもあれば、同時に義務でもある。

I just came across this sentence in my textbook. I notice that the sentence use "でも" instead of simply "も." What's the difference between "でも" and "も" in this context?