Three coins are tossed once. What is the probability of getting a doublet?

why should we consider (HHH) and (TTT) be
Does a doublet contain only two coins to have the same outcome 
shouldn't the third coin be different? I am just not clear about this.
Only two similar outcomes are necessary for a doublet... so long as two outcomes are similar, the third one doesn't matter


The Brainliest Answer!
Total no. of possibilities = 2^(no. of coins) = 2^3 = 8

Possibilities that involve a doublet on tossing 3 coins = 
(HHH), (HHT), (HTH), (THH), (TTH), (THT), (HTT), (TTT)

No. of preferred possibilities = 8

Therefore, probability of getting a doublet = 8/8 = 1 or 100%
2 5 2
Probability of getting a doublet is 1