There is no difference of 1 rupee. The 2 rs value is incorrect.
The first man is getting 1/3 rs per egg.
The second man is getting 1/2 rs per egg.
Combined, they are getting (1/3 + 1/2) / 2 = 5/12 rs per egg.
Their average price is 5 rs per 12 eggs, not 2 rs per 5 eggs.
When they sell 60 eggs, they get 60 (5/12) = 25 rs.
No missing rupee.