Instead of looking at the Bitcoin app as a 'wallet' that holds 'coins' it's better to look at it as a 'bankbook' that holds 'ledger entries'. Each address does not 'hold' coins but rather is a ledger entry that describes the ownership of those coins. The sum total of those ledger entries is what is displayed as your Balance in the Bitcoin application. What you are describing as 'coins being sent from two addresses' is really the combination of two ledger entries in the same bankbook which total 21.881 BTC.
wow, very good way to put it and very clear thank you again!