There are secret albums on the platform, what gives for this tidbit?

[minimumhatred]

Let me explain: (Also if I posted this in the wrong area, I'm sorry, first post :/)

So a couple of months ago I downloaded an Album that wasn't avaliable on Spotify [JAY-Z - The Bluprint], interestingly enough, I hadn't noticed this before but most local files are grey around the album but these songs were white, so I clicked on the album and it showed "The Blueprint, I added it to my albums, which was pretty sweet, but what gives for this tidbit? Are there other albums that work like this? I find it pretty cool, but I want to know what is going on.

Proof: 

[minimumhatred]

I mean one song clearly didn't work but still interesting O.o

Here is a list of other albums that have worked for this: (Yes most of the songs I have imported are rap):

The Chronic by Dr Dre

Reasonable Doubt by JAY-Z

Magna Carta Holy Grail by JAY-Z
The Blueprint by JAY-Z (As pictured above)
The Blueprint 3 by JAY-Z

[minimumhatred]

Answers please?

[badhaircutboy]

Ok I looked this up wondering the same thing myself (as the same happened with me on other songs) so what I say is not the definite answer. but I think it may be that the songs did exist on Spotify but were removed then by downloading it from local files noticed form song recognition that it already existed on their servers even though it was removed. I believe this is because if you get a song that already exists from local files it will try to match it to a song that they already had to avoid doubling up. This also makes sense as jay-z in particular removed all his songs for his music service. Anyway hope that made sense Ik it's a bit late. 🙂