SAFCON and LOAD LINE surveys has a lot in common and both comes under HSSC. And both the surveys are carried out by the class. Does in real world both the surveys conducted together? Or all together included in class special survey?

Yes, these two surveys are usually conducted at the same time along with many other statutory surveys. But that is not a requirement to have these two surveys conducted together. These can be conducted on different dates.

But all these certificates would remain valid for the same duration, which will also be the anniversary date under the harmonized system of survey and certification (HSSC).