diff --git a/app/code/Magento/AdminNotification/Model/ResourceModel/Inbox.php b/app/code/Magento/AdminNotification/Model/ResourceModel/Inbox.php
index 40b089d947136..ac6807007f79f 100644
--- a/app/code/Magento/AdminNotification/Model/ResourceModel/Inbox.php
+++ b/app/code/Magento/AdminNotification/Model/ResourceModel/Inbox.php
@@ -98,12 +98,17 @@ public function parse(\Magento\AdminNotification\Model\Inbox $object, array $dat
 
             if (empty($item['url'])) {
                 $select->where('url IS NULL');
+                unset($item['url']);
             } else {
                 $select->where('url = ?', $item['url']);
             }
 
             if (isset($item['internal'])) {
-                $row = false;
+                if ($item['internal']) {
+                    $row = false;
+                } else {
+                    $row = $connection->fetchRow($select);
+                }
                 unset($item['internal']);
             } else {
                 $row = $connection->fetchRow($select);
diff --git a/app/code/Magento/AdminNotification/Test/Unit/Model/ResourceModel/InboxTest.php b/app/code/Magento/AdminNotification/Test/Unit/Model/ResourceModel/InboxTest.php
new file mode 100644
index 0000000000000..8980d6cc299a5
--- /dev/null
+++ b/app/code/Magento/AdminNotification/Test/Unit/Model/ResourceModel/InboxTest.php
@@ -0,0 +1,214 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\AdminNotification\Test\Unit\Model\ResourceModel;
+
+use Magento\AdminNotification\Model\ResourceModel\Inbox;
+use Magento\Framework\App\ResourceConnection;
+use Magento\Framework\DB\Adapter\AdapterInterface;
+use Magento\Framework\DB\Select;
+use Magento\Framework\Model\ResourceModel\Db\Context;
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager as ObjectManagerHelper;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+
+class InboxTest extends TestCase
+{
+    /**
+     * @var Inbox
+     */
+    private $inbox;
+
+    /**
+     * @var ObjectManagerHelper
+     */
+    private $objectManagerHelper;
+
+    /**
+     * @var MockObject|AdapterInterface
+     */
+    private $mockedConnection;
+
+    protected function setUp()
+    {
+        parent::setUp();
+        $mockedSelect = $this->getMockBuilder(Select::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $mockedSelect->method('from')->willReturnSelf();
+        $mockedSelect->method('where')->willReturnSelf();
+        $this->mockedConnection = $this->getMockBuilder(AdapterInterface::class)
+            ->getMock();
+        $this->mockedConnection
+            ->method('select')
+            ->willReturn($mockedSelect);
+        /** @var ResourceConnection|MockObject $mockedResourceConnection */
+        $mockedResourceConnection = $this->getMockBuilder(ResourceConnection::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $mockedResourceConnection
+            ->method('getConnection')
+            ->willReturn($this->mockedConnection);
+        /** @var Context|MockObject $mockedContext */
+        $mockedContext = $this->getMockBuilder(Context::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $mockedContext
+            ->method('getResources')
+            ->willReturn($mockedResourceConnection);
+        $this->objectManagerHelper = new ObjectManagerHelper($this);
+        $this->inbox = $this->objectManagerHelper->getObject(
+            Inbox::class,
+            [
+                'context' => $mockedContext,
+            ]
+        );
+    }
+
+    public function testParse()
+    {
+        // Setup:
+        $mockedInbox = $this->getMockBuilder(\Magento\AdminNotification\Model\Inbox::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $fakeData = [
+            [
+                'severity' => 1,
+                'date_added' => '2021-01-01 12:00:00',
+                'title' => 'Foo',
+                'description' => 'Bar',
+                'url' => 'http://www.example.com',
+                'internal' => true,
+            ],
+        ];
+
+        // Set expectations:
+        $this->mockedConnection
+            ->expects($this->never())
+            ->method('fetchRow');
+        $this->mockedConnection
+            ->expects($this->once())
+            ->method('insert')
+            ->with(
+                null,
+                [
+                    'severity' => 1,
+                    'date_added' => '2021-01-01 12:00:00',
+                    'title' => 'Foo',
+                    'description' => 'Bar',
+                    'url' => 'http://www.example.com',
+                ]
+            );
+
+        // Exercise:
+        $this->inbox->parse($mockedInbox, $fakeData);
+    }
+
+    public function testNotificationWithoutUrlIsNulled()
+    {
+        // Setup:
+        $mockedInbox = $this->getMockBuilder(\Magento\AdminNotification\Model\Inbox::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $fakeData = [
+            [
+                'severity' => 1,
+                'date_added' => '2021-01-01 12:00:00',
+                'title' => 'Foo',
+                'description' => 'Bar',
+                'url' => '',
+                'internal' => true,
+            ],
+        ];
+
+        // Set expectations:
+        $this->mockedConnection
+            ->expects($this->never())
+            ->method('fetchRow');
+        $this->mockedConnection
+            ->expects($this->once())
+            ->method('insert')
+            ->with(
+                null,
+                [
+                    'severity' => 1,
+                    'date_added' => '2021-01-01 12:00:00',
+                    'title' => 'Foo',
+                    'description' => 'Bar',
+                ]
+            );
+
+        // Exercise:
+        $this->inbox->parse($mockedInbox, $fakeData);
+    }
+
+    public function testInternalNotificationsWithIdenticalDataAreStored()
+    {
+        // Setup:
+        $mockedInbox = $this->getMockBuilder(\Magento\AdminNotification\Model\Inbox::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $fakeData = [
+            [
+                'severity' => 1,
+                'date_added' => '2021-01-01 12:00:00',
+                'title' => 'Foo',
+                'description' => 'Bar',
+                'internal' => true,
+            ],
+        ];
+
+        // Set expectations:
+        $this->mockedConnection
+            ->expects($this->never())
+            ->method('fetchRow');
+        $this->mockedConnection
+            ->expects($this->once())
+            ->method('insert')
+            ->with(
+                null,
+                [
+                    'severity' => 1,
+                    'date_added' => '2021-01-01 12:00:00',
+                    'title' => 'Foo',
+                    'description' => 'Bar',
+                ]
+            );
+
+        // Exercise:
+        $this->inbox->parse($mockedInbox, $fakeData);
+    }
+
+    public function testNonInternalNotificationsWithIdenticalDataAreNotStored()
+    {
+        // Setup:
+        $mockedInbox = $this->getMockBuilder(\Magento\AdminNotification\Model\Inbox::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $fakeData = [
+            [
+                'severity' => 1,
+                'date_added' => '2021-01-01 12:00:00',
+                'title' => 'Foo',
+                'description' => 'Bar',
+                'internal' => false,
+            ],
+        ];
+        $this->mockedConnection
+            ->method('fetchRow')
+            ->willReturn($fakeData);
+
+        // Set expectations:
+        $this->mockedConnection
+            ->expects($this->never())
+            ->method('insert');
+
+        // Exercise:
+        $this->inbox->parse($mockedInbox, $fakeData);
+    }
+}