[Exploit] FC Crafting without turning in every item needed

Time: june 29, 2015 around 0:15am (GMT-3)
Frequency: happened once and could not reproduce
World name: Goblin
Character name: Mestre Kame
NPC name: n/a
Monster name: n/a
Class/Level: ARM50
Party or solo: party
In-game time: 12:15am
Area and coordinates: Company Workshop - Mist (6,6)
Steps:

We were crafting an Invincible-type Hull and were on last phase.
This part requires:

-Mythril Rivets x18
-Cobalt Ingot x18
-Rose Gold Ingot x21
-Varnish x18

We were able to finish the craft delivering only 12/18 Varnish and somehow it was possible to turn in 24 Cobalt Ingot, thus, displaying 24/18 as shown below

http://i.imgur.com/4LMrglJ.jpg

Steps
1. In the last turn-in for an item have two or more party members turn in items simultaneously. Eventually the error message won't be displayed and the amount of item delivered will be higher than the amount needed, counting towards the total turnin's needed to finish the craft.
2. The game seems to count the amount of successful turn-ins and not the items itself. So since there were 12 turns-ins in total, the advance phase option was displayed when only 12/18 Varnish were placed.