Ensure we don't register the TfNotice callback twice MAXTOA-1824 (#2089)

* Ensure we don't register the TfNotice callback twice MAXTOA-1824

* Update changelog

* Fix changelog

CHANGELOG.md

@@ -2,6 +2,9 @@
 # Changelog
 
 ## Pending next bugfix release
+- [usd#2090](https://github.com/Autodesk/arnold-usd/issues/2090) - Fixed crashes when registering the TfNotice callback multiple times
+
+## [7.3.4.0] - 2024-08-30
 - [usd#2075](https://github.com/Autodesk/arnold-usd/issues/2075) - Ensure options attributes are not set while a hydra render is in progress
 
 ## [7.3.3.1] - 2024-08-09

libs/translator/reader/reader.cpp

@@ -568,9 +568,12 @@ void UsdArnoldReader::ReadStage(UsdStageRefPtr stage, const std::string &path)
     // to be informed of the interactive changes happening in the UsdStage
     // (which must be kept in memory)    
     if (_interactive) {
-        _objectsChangedNoticeKey =
-            TfNotice::Register(TfCreateWeakPtr(&_listener),
+        // only register the callback if it wasn't already done
+        if (!_objectsChangedNoticeKey.IsValid()) {
+            _objectsChangedNoticeKey =
+                TfNotice::Register(TfCreateWeakPtr(&_listener),
                 &StageListener::_OnUsdObjectsChanged, _stage);
+        }
         // The eventual "root path" is needed, since we want to ignore changes
         // that aren't part of it
         _listener._rootPath = _hasRootPrim ? _rootPrim.GetPath() : SdfPath();