At the moment, if an item is in the "wrong place" during an inventory, it will show up with a "problem" of "Item should not have been scanned", which makes sense.
However, a duplicate row will also turn up saying "Change item status". This is a row that comes up due to a bug in the processing of not for loan values http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=12913.
In other words... an item might have multiple problems, but instead of listing multiple problems, an entire extra row gets added to the inventory results.
I suppose this could be by design, but it seems like a bug to me, especially if you're feeding your inventory results into "Batch Item Modify" later...
It might be worth adding that http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=14399 makes it so that you can get triple result rows for a single item...
I imagine this might take a fair bit of refactoring to get working...
The problem with Change item status-lines is now resolved on bug 12913.
I will address the Item missing-problem on bug 14399.
That makes this bug a duplicate, since we would only keep one line for the wrongly placed item.
*** This bug has been marked as a duplicate of bug 14399 ***