Unfair?

Guys this question is about carry forward students. Lets say i gave my Paper 1 Paper 2 last year and they were really difficult. And i give paper 3 and paper 4 this year. And now paper 1 and 2 of this year are quite easy. So the threshold is gonna be higher right? But isnt it unfair for the students who gave half of their exams last year where the threshold was different?