diff --git a/lib/Phpfastcache/Core/Pool/ExtendedCacheItemPoolTrait.php b/lib/Phpfastcache/Core/Pool/ExtendedCacheItemPoolTrait.php
index 8316487a3..648508751 100644
--- a/lib/Phpfastcache/Core/Pool/ExtendedCacheItemPoolTrait.php
+++ b/lib/Phpfastcache/Core/Pool/ExtendedCacheItemPoolTrait.php
@@ -50,7 +50,7 @@ public function getItemsByTag($tagName): array
         if (\is_string($tagName)) {
             $driverResponse = $this->getItem($this->getTagKey($tagName));
             if ($driverResponse->isHit()) {
-                $items = (array)$driverResponse->get();
+                $items = (array) $driverResponse->get();
 
                 /**
                  * getItems() may provides expired item(s)
@@ -80,13 +80,13 @@ public function getItemsByTags(array $tagNames): array
         $items = [];
         foreach (\array_unique($tagNames) as $tagName) {
             if (\is_string($tagName)) {
-                $items = \array_merge($items, $this->getItemsByTag($tagName));
+                $items[] = $this->getItemsByTag($tagName);
             } else {
                 throw new PhpfastcacheInvalidArgumentException('$tagName must be a a string');
             }
         }
 
-        return $items;
+        return \array_merge([], ...$items);
     }
 
 
@@ -98,7 +98,7 @@ public function getItemsByTagsAll(array $tagNames): array
         $items = $this->getItemsByTags($tagNames);
 
         foreach ($items as $key => $item) {
-            if (\array_diff($tagNames, $item->getTags())) {
+            if (\array_diff($tagNames, $item->getTags()) || \array_diff($item->getTags(), $tagNames)) {
                 unset($items[$key]);
             }
         }
diff --git a/tests/issues/Github-713.test.php b/tests/issues/Github-713.test.php
new file mode 100644
index 000000000..18b874187
--- /dev/null
+++ b/tests/issues/Github-713.test.php
@@ -0,0 +1,41 @@
+<?php
+
+/**
+ * @author Khoa Bui (khoaofgod)  <khoaofgod@gmail.com> https://www.phpfastcache.com
+ * @author Georges.L (Geolim4)  <contact@geolim4.com>
+ */
+
+use Phpfastcache\CacheManager;
+use Phpfastcache\Drivers\Files\Config as FilesConfig;
+use Phpfastcache\Helper\TestHelper;
+
+chdir(__DIR__);
+require_once __DIR__ . '/../../vendor/autoload.php';
+$testHelper = new TestHelper('Github issue #713 - Api Method "deleteItemsByTagsAll()" removes unrelated items');
+$cacheInstance = CacheManager::getInstance('Files', new FilesConfig(['securityKey' => 'test-713']));
+$cacheInstance->clear();
+
+$item1 = $cacheInstance->getItem('item1');
+$item2 = $cacheInstance->getItem('item2');
+
+$item1->addTags(['shared', 'custom1']);
+$item1->set(1337);
+
+$item2->addTags(['shared']);
+$item2->set(1337);
+
+$cacheInstance->saveMultiple($item1, $item2);
+$cacheInstance->detachAllItems();
+unset($item1, $item2);
+$cacheInstance->deleteItemsByTagsAll(['shared']);
+
+$item1 = $cacheInstance->getItem('item1');
+$item2 = $cacheInstance->getItem('item2');
+
+if ($item1->isHit()) {
+    $testHelper->printPassText('Item #1 is still in cache as expected.');
+} else {
+    $testHelper->printFailText('Item #1 is no longer in cache and so has been unexpectedly removed.');
+}
+
+$testHelper->terminateTest();
\ No newline at end of file