Density functional theory (DFT) calculations are carried out to determine the geometries and electronic and nonlinear optical (NLO) properties of the doubly doped gold clusters in three charge states M2 @ Au17 q with M = W, Mo and q = 0, ±1. At their lowest-lying equilibrium structures, the impurities that are vertically encapsulated inside a cylindrical gold framework, significantly enhance the stability and modify properties of the host. The presence of M2 units results in the formation of a tube-like ground state, which is identified for the first time for gold clusters. Having 30 itinerant electrons, the electron shell of M2@Au17 − can be described as 1S2 1P6 1D102S2 {1Fxz2 2 1F yz2 2 }1Fz3 2 {1Fxyz 2 1Fz(x2 −y 2 ) 2 }{1Fy(3x 2 −y 2 ),1Fx(x 2 −3y 2 )}. The species is thus stabilized upon doping, but it is not a magic cluster. The optical transitions are shifted to the lowerenergy region upon doping Mo and W atoms into Au17 q . The static and dynamic NLO properties of M2@Au17 q are also computed and compared to those of the pure Au19 q (having the same number of atoms) and an external reference molecule, i.e., para-nitroaniline (p-NA). For hyperpolarizabilities, the doped clusters possess smaller values than those of their pure counterparts but much larger values than the p-NA. Of the doubly doped systems, the neutral M2@Au17 exhibits particularly high first and second hyperpolarizability tensors. The doped cluster units can also be used as building blocks for the design of gold-based nanowires with outstanding electronic and optical characteristics.