Annotate duplicate array_key_exists assertType with '// could be true'

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: 2 people

tests/PHPStan/Analyser/nsrt/bug-14705.php

@@ -142,7 +142,7 @@ public function arrayKeyExistsDuplicateInLoop(array $theInput, array $theTags):
 				continue;
 			}
 			assertType('false', !array_key_exists($tag, $theInput));
-			assertType('bool', array_key_exists($tag, $theInput));
+			assertType('bool', array_key_exists($tag, $theInput)); // could be true
 		}
 	}