They releaed Metheny/Mehldau last year (mainly duos, plus a couple of quartet tracks)
They release Metheny/Mehldau Quartet next week (mainly quartet, plus a few duos)
In the spirit of repackage, repackage, repackage, they release something that combines the above in one package latter in the month.
Well, assume that is the case, otherwise there will be a lot of angry people who bought the individual releases.