How to get 3x Mystil & 3x Imperial Guard

There have been rumours for a while where people claimed that the Northern Crather Item Duplication Trick will not work for the PC version. This is false, this works on any international version (every version is considered "International" that does not happen to be the first Japanese release).
Reminder: Some patches like the Reunion mod fix a lot of bugs, this one included. Since Item Duplication was not intended by the devs some mods and patches fix this bug and thus it no longer works.

Basically, when you are in the Northern Crater, you will get to two intersections where you need to chose where your teammates shall go. You get different items on the meetup depending on where you sent them. If you sent Yuffie alone, meaning noone else that went with her, she will lie that she didn't find anything and will keep the item or materia to herself. If you sent someone with her, she will try to lie but a character that went with her will make sure she's giving you what she found.

What a sneaky little ninja!! =)

At the first intersection you can send your party members either left or right, if you sent them left and went left yourself too, you have to decide if you want to send them up or down at the 2nd intersection. If you went right, but send them left, they will randomly go either up or down at the 2nd intersection, which we don't want.

• Put Cait Sith and Vincent into your Party

• Make sure you put Vincent and Cait Sith in your party.
  
• Proceed in the game until you reach the first intersection. Obviously you wanna take all the chests.
  
• Send Cloud left.
  
• Send Tifa right.
  
• Send anybody else left.
  
• Now choose your party of Vincent and Cait Sith again and head left.
  
• You are now at the 2nd intersection.
  
• Send Cloud down.
  
• Send Barret up.
  
• Send Red XIII up.
  
• Send Cait Sith down.
  
• Send Yuffie up.
  
• Send Vincent down.
  
• Send Cid Up.
  
• Take the bottom (down) fork.
  
• When you get to a place with a big yellow crater in the middle, open the chest on the right side and go back again to the intersection. DO NOT PROCEED TO THE BOTTOM DOWN SIDE OF THE SCREEN OR THIS TRICK WILL NOT WORK!
  
• Back at the intersection, take the upper route and collect all the treasures you come across.
  
• Once you went through the whole route, you will get to the same place i just told you to not proceed further in. Follow my advice again and go waaaay back to the very first intersection. Take the right way you send Tifa to. Again, get all the treasures, including a very precious Mystile.
  
• At this place, you will meet a foe named Dragon Zombie. Before that happens, equip one character with all 4 Enemy Skill materias, The reason we are doing this is because after his very first death, the dragon zombie will cast Pandora's Box for the first and last time(!), an Enemy Skill you will never get again if you miss it now! If one character has all Enemy Skills Materia equipped, all of those will get the Pandora's Box. He also casts Shadow Flare sometimes, so get thatt here too if you didn't get it from Ultimate Weapon.
  
• At the end of this you should be at that dreaded place again of which I warned you all the time. If you collected all treasures in the Northern Canve, you can finally head downleft clockwise this time and gather up with your party members.
  
• Talk to each of them, they will give you the item they found (except Cait Sith and Vincent because they went with us).
  The items you will get are the following:
  Tifa: Mystile
  Barret: Vaccine
  Red XIII: Shield Materia
  Cid: Imperial Guard
  Yuffie: Counter Materia
  
• Don't walk to the bottom of this screen or you will face the last boss battle and won't be able to save your progress anymore.
  
• The reason we waited so long to gather with our teammates is that once you gather up with them, you won't be able to loot any treasure in the Northern Crater. That way we wouldn't get a 2nd copy of Mystile here.

That's it! You have 3 Mystile's now, you found your first one in the Midgar Raid at the end of Disc 2 after fighting the Prod Cloud. The second one was found in the Northern crater, right side at the first intersecion. The third one was given to you by TIfa! Same with the Imperial Guard, except that you got your first one at the final battle of Fort Condor during the Huge Materia Quest against CMD.Grand Horn.