diff --git a/src/Preprocessor.php b/src/Preprocessor.php
index 95783251..6e342245 100644
--- a/src/Preprocessor.php
+++ b/src/Preprocessor.php
@@ -695,7 +695,14 @@ class Preprocessor extends CompilerBase
             $flags = Modifiers::PUBLIC;
         }
         if (isset($this->symbolDeclInFile[$fullClassNameLower])) {
-            $this->fatalError($class, "Duplicate class `{$fullClassName}`");
+            // AOT-tolerant duplicate handling: PHP autoloading only ever loads
+            // one declaration of a given FQN at runtime, so cross-file
+            // duplicates (common in frameworks like ThinkPHP, where several
+            // packages ship an identical copy of the same class) are not a
+            // fatal error. Keep the first declaration and skip the rest.
+            $this->warning($class, "Duplicate class `{$fullClassName}` (also declared in {$this->symbolDeclInFile[$fullClassNameLower]}); keeping the first declaration.");
+            $this->resetClass();
+            return '';
         }
 
         $this->classDef = new ClassDef($this->class, $flags, $this->namespace);
@@ -1505,7 +1512,10 @@ class Preprocessor extends CompilerBase
         }
 
         if (isset($this->symbolDeclInFile[$interfaceNameLower])) {
-            $this->fatalError($v, "Duplicate interface `{$interfaceName}`");
+            // Same AOT-tolerant handling as classes: keep the first declaration
+            // of a duplicated interface FQN and skip the rest.
+            $this->warning($v, "Duplicate interface `{$interfaceName}` (also declared in {$this->symbolDeclInFile[$interfaceNameLower]}); keeping the first declaration.");
+            return;
         }
 
         $this->symbolDeclInFile[$interfaceNameLower] = $this->file;