Outlook 2013 Duplicating Attendees

I have a user who when adding a contact to an existing meeting ends up with the people already on the meeting request getting duplicated.  

For example, Person A and Person B are already part of the meeting.  She adds Person C and now the meeting shows Person A, Person B, Person C, Person A, Person B, as attending the meeting.  

Office is fully patched.  She uses an Android phone to view her calendar but does not manage or create meetings via the phone.
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C. Blaise MitsutamaFounder/Principal | Technical Writing | Editing | Training | Design | Presentation | StartupsCommented:
Are the recipients with duplicate entries invited using a Distribution List? Are they internal or external recipients?

This Knowledge Base article may offer some clues: Article ID: 924249.

When a meeting request is accepted by an external recipient and that recipient has an entry in the global address list (GAL), the originator will see the recipient's name on the Scheduling Tab of the meeting request.

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brhuntAuthor Commented:
They are external attendees.  Sorry for the delay in getting back to you.
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