Generally speaking, it is necessary. In pre-defense, papers are usually submitted to the graduate system, because the paper submission module in the graduate system is also divided into many different time points, that is, the submission of the first draft, the intermediate draft and the last graduation thesis is divided into different modules.

Then different papers will be handed in at different time points, so the papers before the defense generally need to be handed in to the graduate system, that is, some graduation systems related to their own schools, and the arrangements of the schools are different.

In other words, in this school, it may be handed over to the postgraduate system, but it may not be used in another school, so the specific words still depend on an arrangement of the tutor and an arrangement of the school's educational affairs.