Why LiveData observer is being triggered twice for a newly attached observer

Question

My understanding on LiveData is that, it will trigger observer on the current state change of data, and not a series of history state change of data.

Answer 1

The reason is that in your .observe() method, you passed a fragment as the lifecycle owner. What should have been passed is the viewLifecycleOwner object of the fragment

viewModel.livedata.observe(viewLifecycleOwner, Observer {
        // Do your routine here
    })