Copy paste multiple triggers by using SCMDraft's TrigEdit. It's in text format, so you can copy paste it, even if you have no idea how the syntax and everything works. You can also copy it into notepad, do a Replace All on "player 1" with "player 2," and THEN copy it back
You cannot have 2 trigedits open, but I suppose you could open both scmdraft's classic trigedit and normal staredit (xtra)'s trigger editor. Just be careful with two editors open at once, because you could very easily accidently save over some work you did in the other editor.
However, what I am saying is that you should not need multiple copies of your triggers. Instead of having multiple copies and changing the player each time, change it to "Current Player." If you click where it says Player 1, an option will say "Current Player," it's not just something I made up. In this way, you could check the players that could run the trigger to Player 1, Player 2, Player 3, and Player 5, so you don't need to copy anything. The only time you do need to copy a unique set for each player is when there is an instance in which the players use their own locations, different units, different computers.. etc. Most triggers, especially in the map you posted, can be done by simply using Current Player and applying the trigger to each player.
Sorry if I confuse you, I'm just trying to help