Issue Description:

Dupe bug when backup is able to be pulled out of inventory while the backpack is open

What happens:

You are able to duplicate and item that is in the backpack

What you expected to happen:

Well a dupe bug to happen

Steps to reproduce (important):

1. Get a player chest, and place it
2. Set chest to take out from one spot in your inv
3. Get some item transfer that can be turned on with redstone
4. Setup item transfer to transfer to a chest
5. place wooden peruse plate to active redstone for pipe
6. Put items in bag, then close bag
7. face the peruse plate and open bag
8. Drop another item form your inventory to trigger plate to remove backup
9. Take items out of backpack
10. Get backback out of chest
11. take items out of that one and boom dupe bug

Video: http://ss.unrealdinnerbone.x10.bz/2018-07-14_16-28-55.mp4
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Affected Versions (Do not use "latest"):

• IronBackpacks: 1.12.2-30.8-12
• Minecraft: 1.12.2
• Forge: 14.23.4.2709
• Other Conflicting Mods (may be irrelevant to your issue): Extra Utils