What does the temp2 destination sync mean?

[arielylim]

Comments in config say: this field will always submit the destination directory as the temporary2 directory. These two directories will be in sync so that they will always be submitted as the same value.

• submit where?
• why would you want the -2 and -d synced?
• if you set this field to true, how does that affect the -2 (temp2) and -d (destination) you set in the previous fields? Won't it make the -t irrelevant?