A pointer to a pointer is rarely usefull, and if you use it, you have to use the address operator on the another pointer when you assign it:
AActor* pointer1 = *whatever*;
AActor** pointer2 = &pointer1; // & address operator
Sometimes you can see ** used for arrays that are filled with pointers. Like char** is actually a pointer to a pointer that points to a character like you can see it is done in the standard C main Function to handle multiple char arrays.
A pointer is a storage for a memory adress( meaning just a number), that additionally tells the compiler what kind of datatype he can expect at that adress. If there is another pointer to a datatype at that address and the original pointer tells this by indicating **, why not.
Your example above is really what you would do with a pointer most times, give it to some other class or use it as function parameter to access the original object. But take care, deleting the original object and then accessing it by a pointer that still has its address will crash.
But back to your original question, if you really need a reference to a pointer and it is no array of pointers, you might consider:
AActor* pointer1 = *whatever*;
AActor*& pointer2 = pointer1; // reference to the pointer
Here are a lot of examples when, why this pointet-to-pointer or reference-to-pointer could we useful and how: Pointer-to-Pointer and Reference-to-Pointer | CodeGuru
Crazy stuff? Welcome to C++