I think this sort of doublethink is terribly common. Daniel Dennett's Breaking the Spell: Religion as a Natural Phenomenon discusses it in relation religion: that people are quite happy to profess the correct supernatural beliefs but behave as if they aren't true. I think there is an awful lot of it in politics too. It is not always a great idea to live by the nostrums of your political tribe, and it is helpful to maintain this separation. I'm less convinced of the example of economics. The important thing is not whether the assumptions behind our models are correct, but to what extent our models are robust against them being incorrect.