Calling LoadFromFile stream in
"bool Load(Event<Stream&> serialize, Stream& stream, int version){ ..."
calls user function "void XUserClass::Serialize(Stream& s){..." twice.
Once with backup.SetStoring(); flag and once with stream.SetLoading();.
Both are called from Core/Stream.cpp at 1287 in "bool Load(Event<Stream&> serialize, ...".

I don't think this is normal, since user callback is fired twice.