During WvWvW pvp, I will use my portal entrance and exit to provide an escape route during situation’s where I am fighting against more than 2 player’s at a time. However on some occasion’s usually whilst under heavy fire/taking a lot of damage, I will place my second portal to escape, however it will not let me activate the teleport or even display the "Use Portal (F).
I understand the second portal is actually called the “Portal Exuent” however I can usually use them in a two way system, rather than one entrance and one portal.