multi: fix typos in comments

lnwallet/btcwallet/btcwallet.go

@@ -260,7 +260,7 @@ func (b *BtcWallet) GetPrivKey(a btcutil.Address) (*btcec.PrivateKey, error) {
 
 // SendOutputs funds, signs, and broadcasts a Bitcoin transaction paying out to
 // the specified outputs. In the case the wallet has insufficient funds, or the
-// outputs are non-standard, a non-nil error will be be returned.
+// outputs are non-standard, a non-nil error will be returned.
 //
 // This is a part of the WalletController interface.
 func (b *BtcWallet) SendOutputs(outputs []*wire.TxOut,