C++ :: Convert Pointer To Plain Object

I have pointer object and i have to assign to another variable ( new object ). But if i change any value in new object should not reflect in old object. I did in the below way, it changes the value.

class Test {
public:
int num;
};
Test* obj;
obj.num=1;
Test obj_n=*obj;
obj_n.num=2;

Now both object's num have value as 2;
i.e
obj.num // has 2
obj_n.num // has 2

Actually my expected result is:
obj.num - should have value 1
obj_n.num - should have value 2

My actual scenario is different where Test obj is pointer object, so obj should be pointer object. i have given sample scenario.