Steps to reproduce:
0. Start Unity Editor on Windows (if you can't reproduce, try using -debugAllocator)
1. Open project from https://fogbugz.unity3d.com/f/cases/edit/1209332
2. Go to Scenes -> Sample Scene
3. Click Generate Lighting

Expected: no crash
Actual: assertion in ShaderVariantCollection code.

Reproduced in: 2020.1.0a19.2395 (6995b659db2e)
Not reproduced in: 2019.3.0f5 (44796c9d3c2c)

Callstack:
Unity.exe!assert_duplicates_and_sorted<std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<ShaderVariantCollection::VariantInfo> > >,std::less<ShaderVariantCollection::VariantInfo> >(std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<ShaderVariantCollection::VariantInfo> > > first, std::_Vector_const_iterator<std::_Vector_val<std::_Simple_types<ShaderVariantCollection::VariantInfo> > > last, std::less<ShaderVariantCollection::VariantInfo> pred) Line 77 C++
Unity.exe!sorted_vector<ShaderVariantCollection::VariantInfo,std::less<ShaderVariantCollection::VariantInfo>,std::allocator<ShaderVariantCollection::VariantInfo> >::verify_duplicates_and_sorted() Line 104 C++
Unity.exe!vector_set<ShaderVariantCollection::VariantInfo,std::less<ShaderVariantCollection::VariantInfo>,std::allocator<ShaderVariantCollection::VariantInfo> >::sort() Line 128 C++
Unity.exe!ShaderVariantCollection::AwakeFromLoad(AwakeFromLoadMode awakeMode) Line 138 C++
Unity.exe!AwakeFromLoadQueue::InvokePersistentManagerAwake(AwakeFromLoadQueue::Item * objects, unsigned int size, AwakeFromLoadMode awakeMode, bool checkConsistency) Line 486 C++
Unity.exe!AwakeFromLoadQueue::PersistentManagerAwakeFromLoad(int queueIndex, AwakeFromLoadMode mode, bool checkConsistency) Line 299 C++
Unity.exe!AwakeFromLoadQueue::PersistentManagerAwakeFromLoad() Line 169 C++
Unity.exe!PersistentManager::IntegrateAllThreadedObjects() Line 1255 C++
Unity.exe!PersistentManager::LoadFileCompletely(const core::basic_string<char,core::StringStorageDefault<char> > & path) Line 2112 C++
Unity.exe!InitializeShaderCompilationManager() Line 142 C++
Unity.exe!InitializeEngineGraphics(bool batch) Line 309 C++
Unity.exe!Application::InitializeProject() Line 950 C++
Unity.exe!WinMain(HINSTANCE__ * hInst, HINSTANCE__ * hPrev, char * szCmdLine, int nCmdShow) Line 942 C++