Hello Diy89Nurm7,
I don't know if you read the beginning of this thread or not, but in a nutshell, the BEP made a mistake and authorized two different printing facilities to print some of these 2013, B New York, $1, Star Notes, with Serial Numbers that had already been printed and sent out into the world. Thus creating roughly 6.4 million possible pairs of notes from the same series, same denomination, and the same FRB, Star Notes. As is well known, a Serial Number is only supposed to be used once per Series, Denomination, and FRB, thus the whole reason for Star Notes being used to denote it being a replacement note for one being replaced. This happening on Star Notes makes it all the more interesting.
Some call this an error, some a mistake, but tomato or tomata in my humble opinion it's semantics, two notes with duplicated serial numbers was an unplanned and out of procedure occurrence, or maybe just an oops.
Again, in my humble opinion, if it were ok to do this because they were printed at two different facilities, then we wouldn't need Star notes for replacements we could just have the other facility print the same serial number there and use it as the replacement. We could also make currency Serial Numbers shorter, by duplicating serial numbers printed at the opposite facility, saving tons of money on ink and equipment set up for large serial numbers, over the course of billions of notes being printed. Only my opinion, I am the Novice when it comes to currency knowledge here.
But I digress, regardless of what anyone wants to call this, it is a project made up of hundreds if not thousands of collectors who are trying to bring notes with matching serial numbers together.
The benefit is for a collector to acquire a matched pair of serial numbered notes. The project helps track and then match up note owners once a pair is identified. It is up to the two owners to work out a buy, sell or trade agreement with each other to own the pair together.
At this point there are 7 matched pairs with individual owners. There are 3 matched pairs with dual ownership.
This is a personal preference if you want to try and get a matched pair or not.


I hope this helps bring the project into context for you!
Again, this is my opinion and it is not shared by all.
If you want an expert opinion on this topic, I suggest you ask SteveInTampa as he is widely held as our currency expert here on the CCF.
I highly respect him and his knowledge on this subject, as he was the one who introduced me to this project!
Thank you for your questions and interest!