importprivkey: do not import the same key twice

gui/qt/main_window.py

@@ -2208,10 +2208,9 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         badkeys = []
         addrlist = []
         for key in text:
-            addr = self.wallet.import_key(key, password)
             try:
                 addr = self.wallet.import_key(key, password)
-            except Exception as e:
+            except BaseException as e:
                 badkeys.append(key)
                 continue
             if not addr:

lib/commands.py

@@ -368,7 +368,7 @@ class Commands:
         try:
             addr = self.wallet.import_key(privkey, self._password)
             out = "Keypair imported: " + addr
-        except Exception as e:
+        except BaseException as e:
             out = "Error: " + str(e)
         return out
 

lib/keystore.py

@@ -115,7 +115,9 @@ class Imported_KeyStore(Software_KeyStore):
         try:
             pubkey = public_key_from_private_key(sec)
         except Exception:
-            raise Exception('Invalid private key')
+            raise BaseException('Invalid private key')
+        if pubkey in self.keypairs:
+            raise BaseException('Private key already in keystore')
         self.keypairs[pubkey] = sec
         return pubkey