exploit [BUG][EXPLOIT] Tekkit 1.2.9f - Duplication bug with Project Bench and Strongbox

[DAVdaBRAV]

Just came across this bug in standard Tekkit 1.2.9f (While playing on a server, not sure if this is relevant).  Not sure if this has been reported but Google didn't bring up anything relevant to it so here we go:

Severity: High (While it does not immediately crash the server or anything like that, this exploit makes it possible for one player to produce infinite resources early in the game and with minimal effort. Solutions involving locking away the affected items are, shall we say, less than ideal.)

Affected Mods (So far):

• Project Bench
• Thermal Expansion
• Backpack

Method:

1. Create at least two Strongboxes and a Project Bench.
2. Put at least 8 Invar Ingots in the Project Bench along with at least one empty Strongbox. (You simply have to have enough resources in the Project Bench to upgrade twice or as many Strongboxes as you plan to upgrade. It doesn't have to be Strongbox to Hardened Strongbox, that's just the easiest upgrade.)
3. Place your Strongbox and put something in it. (This can be anything, a piece of dirt, cobble, 18 other Strongboxes filled with 18 Backpacks each filled with 18 stacks of Diamond Blocks each...)
4. Sneak + Right-click your Strongbox with a Crecent Hammer to pick it up.
5. Place your full Strongbox in the middle of the crafting grid on the Project Bench and surround it with 4 Invar Ingots.
6. Pull out your newly upgraded full Hardened Strongbox and subsequently pull out your newly upgraded empty Hardened Strongbox(es).
7. Notice that the formally empty Strongboxes have been upgraded to Hardened Strongboxes each of which happen to also contain duplicates of whatever was in the originally upgraded Strongbox.

Replication Rate: 100% (So far, I've only done a few tests)

Effects multi-player!

TL;DR: Upgrading a Strongbox with items inside using a Project Bench and immediately upgrading an empty Strongbox causes all contents from the full Strongbox to be duplicated to the empty Strongbox after the upgrade.

Please attempt to replicate my results, and post.

Edited June 8, 2015 by DAVdaBRAV
Typos