Ab initio MP2/6-311G** and QCISD(T)/6-311G** levels as well as Gaussian-2 theory were used to perform a comparative study of the structures and stabilities of the ethane dication C2H62+ and its silicon analogues Si2H62+ and CSiH62+. Similar to previous HF/6-31G* results, our present calculations also indicate that the two-electron three-center (2e-3c) bonded carbonium-carbenium structure 1 is more stable than the doubly hydrogen bridged diborane-type structure 2 by about 12 kcal/mol. For the silicon analogue Si2H62+ the calculations, however, indicate that the 2e-3c bonded siliconium-silicenium structure 8 is about 9 kcal/mol less stable than doubly hydrogen bridged structure 9. Similar results were also computed for carbon-silicon mixed CSiH62+ dication structures. These studies are in agreement with the more electropositive character of silicon compared to carbon. Possible dissociation paths of the minimum structures were also calculated.