Serialize, then deserialize, vs. deserialize, then serialize: Which order and why?

Working for a new company and I'm learning how they do what they do and why they do it. I've noticed that when setting u the sorting for their grids, they sometimes DE-serialize then serialize, and sometimes they do the opposite. I have done sorting on grids before in C# but have not had to use serialization or DE-serialization so, I'm just trying to get a better understanding of when and why you would want to use this technique? If a brief summary of this can be given that will suffice, otherwise some links on why and why the order matters would be great. Thanks in advance.