I now have two copies of the same song in iTunes. One is "Matched" and one is "Purchased." How do I remove one, and which one should I remove?

Question

I subscribe to iTunes Match.  One day a couple months ago I noticed that my iTunes library was populated by a new collection of songs.  Songs I already had and were identified as Matched.  All of a sudden, I not only had the"Matched" copy, but also another copy labelled "Purchased."  When I went to "View" --> Duplicates, sure enough there was about 180 songs that had been added to duplicates.  All 180 were identified as "Purchased" and all were identified as purchased on the same date.  That common date was often several years after the date associated with the Matched version.  ALL had the SAME purchase date.  No one in our house of 4 Mac computers sharing the same Apple Account and having the same iTunes libraries had purchased any songs on that date...7/19/13.  All at around 10:30 PM, plus or minus a minute.
Has anyone had this same experience?  I tried to remove the "Matched" copy of each song knowing that the "Purchased" copy would not count to my iTunes Match total.  But, that didn't work.  It appears I am stuck with both copies.
When the recent update to iTunes (v11.0.5) came out, I thought it may address this issue.  No go.  I still have all these duplicates of the same song.  I mean...THE SAME SONG!  AT least as far as I can tell by checking all the information associated with each.  Same name,  same artist, same everything.  As far as I can tell, there is nothing that could "fake out" iTunes Match to think these were different versions.
And ideas what happened and what I can do?

Answer 1

Hello mracole,
I checked my "purchases" and the 7/19/13 purchases don't show up.  However, the earlier versions from usually several years back...the ones that are Matched...often do show up in my Purchases.  I suspect that somehow those REALLY purchased several year old versions were deleted and redownloaded by me so I could change them to the 256 kbps versions under iTunes Match.  They were probably 128 kbps versions originally when purchased.
Why the earlier versions that were really purchased are now identified as Matched is puzzling.
Why I now have Purchased versions from 7/19/13 is puzzling too...especially since these versions do NOT show up in my purchases.
Calling Apple Support if a good idea unless someone can explain this mystery.  I might even take one of my laptops to the Apple store and show a Genius.
Thank you very much for taking the time to respond, Mr. Luigi