This fixes the ResultSet trying to hydrate a result twice.

Still results are being nested incorrectly, though

src/ORM/Association.php

@@ -14,6 +14,7 @@
  */
 namespace Cake\ORM;
 
+use Cake\Database\Expression\IdentifierExpression;
 use Cake\Datasource\ResultSetDecorator;
 use Cake\Event\Event;
 use Cake\ORM\Entity;

src/ORM/Association/BelongsToMany.php

@@ -49,13 +49,6 @@ class BelongsToMany extends Association {
  */
 	const SAVE_REPLACE = 'replace';
 
-/**
- * Whether this association can be expressed directly in a query join
- *
- * @var boolean
- */
-	protected $_canBeJoined = false;
-
 /**
  * The type of join to be used when adding the association to a query
  *

src/ORM/Association/ExternalAssociationTrait.php

@@ -14,7 +14,6 @@
  */
 namespace Cake\ORM\Association;
 
-use Cake\Database\Expression\IdentifierExpression;
 use Cake\ORM\Association\SelectableAssociationTrait;
 use Cake\ORM\Query;
 use Cake\Utility\Inflector;

src/ORM/Association/HasOne.php

@@ -14,7 +14,6 @@
  */
 namespace Cake\ORM\Association;
 
-use Cake\Database\Expression\IdentifierExpression;
 use Cake\ORM\Association;
 use Cake\ORM\Association\DependentDeleteTrait;
 use Cake\ORM\Association\SelectableAssociationTrait;

src/ORM/Association/SelectableAssociationTrait.php

@@ -79,7 +79,6 @@ protected function _buildQuery($options) {
 		$target = $this->target();
 		$alias = $target->alias();
 		$key = $this->_linkField($options);
-
 		$filter = $options['keys'];
 
 		if ($options['strategy'] === $this::STRATEGY_SUBQUERY) {

src/ORM/EagerLoader.php

@@ -67,6 +67,13 @@ class EagerLoader {
  */
 	protected $_loadExternal = [];
 
+/**
+ * Contains a list of the association names that are to be eagerly loaded
+ *
+ * @var array
+ */
+	protected $_aliasList = [];
+
 /**
  * Sets the list of associations that should be eagerly loaded along for a
  * specific table using when a query is provided. The list of associated tables
@@ -318,7 +325,14 @@ protected function _normalizeContain(Table $parent, $alias, $options, $paths) {
 			'aliasPath' => trim($paths['aliasPath'], '.'),
 			'propertyPath' => trim($paths['propertyPath'], '.'),
 		];
+
 		$config['canBeJoined'] = $instance->canBeJoined($config['config']);
+		if ($config['canBeJoined'] && !empty($this->_aliasList[$alias])) {
+			$config['canBeJoined'] = false;
+			$config['config']['strategy'] = $instance::STRATEGY_SELECT;
+		}
+
+		$this->_aliasList[$alias][] = $paths['aliasPath'];
 
 		foreach ($extra as $t => $assoc) {
 			$config['associations'][$t] = $this->_normalizeContain($table, $t, $assoc, $paths);

tests/TestCase/ORM/QueryRegressionTest.php

@@ -67,13 +67,20 @@ public function testEagerLoadingFromEmptyResults() {
 	}
 
 	public function testDuplicateAttachableAliases() {
+		TableRegistry::get('Stuff', ['table' => 'tags']);
+		TableRegistry::get('Things', ['table' => 'articles_tags']);
+
 		$table = TableRegistry::get('Articles');
 		$table->belongsTo('Authors');
-		$table->hasOne('ArticlesTags');
-		$table->Authors->target()->hasOne('Tags', ['foreignKey' => 'id']);
-		$table->ArticlesTags->target()->belongsTo('Tags', ['foreignKey' => 'tag_id']);
+		$table->hasOne('Things');
+
+		$table->Authors->target()->hasOne('Stuff', ['foreignKey' => 'id']);
+		$table->Things->target()->belongsTo('Stuff', ['foreignKey' => 'tag_id']);
 
-		$results = $table->find()->contain(['Authors.Tags', 'ArticlesTags.Tags']);
+		$results = $table->find()
+			->contain(['Authors.Stuff', 'Things.Stuff'])
+			->hydrate(false)
+			->toArray();
 	}
 
 }