eliminating double words

ch04_keys.adoc

@@ -420,7 +420,7 @@ y = 07CF33DA18BD734C600B96A72BBC4749D5141C90EC8AC328AE52DDFE2E505BDB
 
 
 Instead of direct public key entry, the earliest version of Bitcoin
-software allowed a spender to enter the the receiver's IP address, as shown in <<bitcoin_01_send>>.  This
+software allowed a spender to enter the receiver's IP address, as shown in <<bitcoin_01_send>>.  This
 feature was later removed--there are many problems
 with using IP addresses--but a quick description of it will help us
 better understand why certain features may have been added to the

ch05_wallets.adoc

@@ -26,7 +26,7 @@ Bitcoin wallets contain bitcoins.  In fact, what many people call a
 Bitcoin wallet--which we call a _wallet database_ to distinguish it
 from wallet applications--contains only keys.  Those keys are associated
 with bitcoins recorded on the blockchain.  By proving to Bitcoin full nodes that you
-control the keys, you can can spend the associated bitcoins.
+control the keys, you can spend the associated bitcoins.
 
 Simple wallet databases contain both the public keys to which bitcoins
 are received and the private keys that allow creating the signatures
@@ -421,7 +421,7 @@ bitcoins.  Deterministic key derivation and recovery codes provide a
 reasonably robust solution for backing up and recovering your keys and
 the bitcoins they control.  However, it's important to consider that
 many wallet databases store more than
-just keys--they also also store user-provided information about every
+just keys--they also store user-provided information about every
 transaction they sent or received.
 
 For example, when Bob creates a new address as part of sending an