Storyline 360: adding in dummy drag items

I have a drag and drop interaction with two unusual features:

1. There are two drag items that can be dropped on either of two drop sites.  I used variables and this part works.

2.  There are 12 drag items and 6 of them don't have matching drop sites.  The problem is that if you don't drop the correct item on the correct site, it doesn't snap to the site.  That makes it really easy to figure out if you have the correct answer before submitting.  I have tried setting Drag & Drop options in different combinations and I can't get the right combination.  

I'm attaching my file in hopes that somebody will be able to help.

UPDATE: I removed the problem file and attached a fixed one in the comments.

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