All DLLs inside the Plugins folder Will be loaded when CDGameShell.exe is executed. When both old and new SGOBattleSys.dll exist simultaneously, gaining experience points during battles still occurs without causing a crash. However, it is uncertain whether potential issues may arise.
e.g. SGOBattleSys_new.dll & SGOBattleSys_old.dll
If concerned about potential issues, simply replacing the old SGOBattleSys.dll should suffice.