What is probability of having double (two dice will show the same number) when we throw 5 dices(all dices have 6 sides)

My calculations are:

Combinations(5,2)*6 / 5^6

And when I try to find probability of having a pair of double ( two dice will show the same number and another two dice will show the same number) when we throw 5 dices calculations are the following:

 Combinations(5,2)*6 / 5^6 * Combinations(3,2)*6 / 5^6 

Is that approach correct or I should try something else?