Sharepoint List - Duplicate Group issue

Hi folks,

I've created a SharePoint list to log internal communications. To group communications by their Date, I've added a calculated column to pull out the Month (XX - Month) from the Date field using a calculated field, formula below:

=CONCATENATE(TEXT(Date,"mm"),"-",TEXT(Date,"mmmm")) 

Now, when I create a new view to group by the calculated Month column, 02 - February is showing up twice, at the top and bottom of the list.

Here's the grouping settings to display in descending order:

And then sort by the Data, again in descending order:

And here's the list view that shows February twice:

And when I select a specific case/record, it shows as if I've selected 2 different records, even though they are the same. 

HELP!