Dual diffeomorphisms and finite distance asymptotic symmetries in 3D gravity

We study the finite distance boundary symmetry current algebra of most general first order theory 3D gravity. show that space quadratic generators contains diffeomorphisms but also a notion dual diffeomorphisms, which together form either double Witt or centerless ${\mathrm{BMS}}_{3}$ algebra. The relationship with usual asymptotic relies on duality between null and angular directions, is possible thanks to existence diffeomorphisms.