The distinction between two individual coins makes no sense. From a trading perspective you bought 1@1 and 1@.5 you now have 2 and paid 1.5 for them. If you sell any of the two for more than .5 you still have more than you had before.
If he is in the U.S. (or elsewhere), it could be relevant to be able to choose your tax lots. Eg you realize a loss on some coins vs a gain on others.
From a technical perspective you are right, but from a tax perspective it could matter. At most brokerages you can say "sell the 100 shares lot of INTC I bought on date X, not the 100 shares I bought on date Y." Even though they are fungible, the government views them differently.
Whether the OP had tax concerns, I don't know. They should let you pick.