Generate random enum without consecutive repetition [C++]

How do I generate random enum values without consecutive repetition?

enum keycode {
    VK_LEFT   = 75,
    VK_UP     = 72,
    VK_RIGHT  = 77,
    VK_DOWN   = 80
};

VK_LEFT, VK_DOWN, VK_UP, VK_RIGHT, VK_DOWN ...

and not

VK_LEFT, VK_DOWN, VK_UP, VK_UP, VK_RIGHT ...