dbghelp: Improve collision handling in SymLoadModuleEx().

dlls/dbghelp/module.c

@@ -969,6 +969,14 @@ DWORD64 WINAPI  SymLoadModuleExW(HANDLE hProcess, HANDLE hFile, PCWSTR wImageNam
         /* we have a conflict as the new module cannot be found by its base address
          * we need to get rid of one on the two modules
          */
+        if (lstrcmpW(module->modulename, altmodule->modulename) != 0)
+        {
+            /* module overlaps an existing but different module... unload new module and return error */
+            WARN("%ls overlaps %ls\n", module->modulename, altmodule->modulename);
+            module_remove(pcs, module);
+            SetLastError(ERROR_INVALID_PARAMETER);
+            return 0;
+        }
         /* loading same module at same address... don't change anything */
         if (module->module.BaseOfImage == altmodule->module.BaseOfImage)
         {
@@ -976,9 +984,10 @@ DWORD64 WINAPI  SymLoadModuleExW(HANDLE hProcess, HANDLE hFile, PCWSTR wImageNam
             SetLastError(ERROR_SUCCESS);
             return 0;
         }
-        module_remove(pcs, module);
-        SetLastError(ERROR_INVALID_PARAMETER);
-        return 0;
+        /* replace old module with new one, which will look like a shift of base address */
+        WARN("Shift module %ls from %I64x to %I64x\n",
+             module->modulename, altmodule->module.BaseOfImage, module->module.BaseOfImage);
+        module_remove(pcs, altmodule);
     }
 
     if ((dbghelp_options & SYMOPT_DEFERRED_LOADS) == 0)