Krishnan Nair asked:
Aniket Yes, it was mentioned more than once. At least twice it was said that officers got confused while delivering their letters to them in their cells. And also it was mentioned that when Danny was handling Nick's chain for him, people mistook him for Nick.
Somantika I had a big problem with this part of the plot and this is why it will never be at the same level as The Count of Monte Cristo. To give a direct answer to the question, I didn't think that their similarity in looks was explicitly mentioned before Nick's death. I can understand that one could mistake one for the other when seen from a distance or from behind especially when wearing the key around the neck and such but I could not buy the fact that Danny just left the prison and started talking, acting, and moving like Nick and even had the same hand writing to the point that there was no doubt.