Django - How does order_by work?

As the other answers correctly explain, order_by() accepts multiple arguments. I'd suggest using something like:

qs.order_by('score','pk') #where qs is your queryset

I recommend using 'pk' (or '-pk') as the last argument in these cases, since every model has a pk field and its value is never the same for 2 records.

order_by can have multiple params, I think order_by('score', '-create_time') will always return the same queryset.

If I understand correctly, I think you need consistently ordered result set every time, You can use something like order_by('score','id') that will first order by the score first and then by the auto-increment id within the score having same values, hence your output being consistent. The documentation is here. You need to be explicit in the order_by if you want to fetch correct result set every time, using 'id' is one of the ways.