diff --git a/packages/accounts-base/accounts_client.js b/packages/accounts-base/accounts_client.js
index 27163cc8d15..29a743dd527 100644
--- a/packages/accounts-base/accounts_client.js
+++ b/packages/accounts-base/accounts_client.js
@@ -281,6 +281,13 @@ Ap.callLoginMethod = function (options) {
       // already logged in they will still get logged in on reconnect.
       // See issue #4970.
     } else {
+      // First clear out any previously set Acccounts login onReconnect
+      // callback (to make sure we don't keep piling up duplicate callbacks,
+      // which would then all be triggered when reconnecting).
+      if (self._reconnectStopper) {
+        self._reconnectStopper.stop();
+      }
+
       self._reconnectStopper = DDP.onReconnect(function (conn) {
         if (conn != self.connection) {
           return;
diff --git a/packages/accounts-base/accounts_reconnect_tests.js b/packages/accounts-base/accounts_reconnect_tests.js
index 30bf469e61e..21d2ab92246 100644
--- a/packages/accounts-base/accounts_reconnect_tests.js
+++ b/packages/accounts-base/accounts_reconnect_tests.js
@@ -7,36 +7,32 @@ if (Meteor.isServer) {
 }
 
 if (Meteor.isClient) {
+  const loginAsUser1 = (onUser1LoggedIn) => {
+    Accounts.createUser({
+      username: `testuser1-${Random.id()}`,
+      password: `password1-${Random.id()}`
+    }, onUser1LoggedIn);
+  };
+
   Tinytest.addAsync('accounts - reconnect auto-login', function(test, done) {
     var onReconnectCalls = 0;
     var reconnectHandler = function () {
       onReconnectCalls++;
     };
     Meteor.connection.onReconnect = reconnectHandler;
-    
-    var username1 = 'testuser1-' + Random.id();
+
     var username2 = 'testuser2-' + Random.id();
-    var password1 = 'password1-' + Random.id();
     var password2 = 'password2-' + Random.id();
     var timeoutHandle;
     var onLoginStopper;
 
-    loginAsUser1();
-
-    function loginAsUser1() {
-      Accounts.createUser({
-        username: username1,
-        password: password1
-      }, onUser1LoggedIn);
-    }
-
-    function onUser1LoggedIn(err) {
+    loginAsUser1((err) => {
       test.isUndefined(err, 'Unexpected error logging in as user1');
       Accounts.createUser({
         username: username2,
         password: password2
       }, onUser2LoggedIn);
-    }
+    });
 
     function onUser2LoggedIn(err) {
       test.isUndefined(err, 'Unexpected error logging in as user2');
@@ -81,4 +77,33 @@ if (Meteor.isClient) {
       done();
     }
   });
+
+  // Make sure that when a logged in user is disconnected then reconnected,
+  // they still only have one Accounts login onReconnect callback set.
+  // Addresses: https://github.com/meteor/meteor/issues/9140
+  Tinytest.addAsync(
+    'accounts - verify single onReconnect callback',
+    function (test, done) {
+      loginAsUser1((err) => {
+        test.isUndefined(err, 'Unexpected error logging in as user1');
+        test.equal(
+          Object.keys(DDP._reconnectHook.callbacks).length,
+          1,
+          'Only one onReconnect callback should be registered'
+        );
+        Meteor.disconnect();
+        test.isFalse(Meteor.status().connected);
+        Meteor.reconnect();
+        setTimeout(() => {
+          test.isTrue(Meteor.status().connected);
+          test.equal(
+            Object.keys(DDP._reconnectHook.callbacks).length,
+            1,
+            'Only one onReconnect callback should be registered'
+          );
+          done();
+        }, 1000);
+      });
+    }
+  );
 }