Songs bought from iTunes and those manually added show up in different albums in Music app There was an album with 5 songs, 3 of them was uploaded to the band's BandCamp, 2 were not.
So I just downloaded the 3 free songs and added them to iTunes library, and bought the other 2 from iTunes. Now, when I added them to my iPhone, They are split into 2 different albums with the same name.

I believe there is something to do with the "Copyright" field in the ID3 of those songs.

Any workaround?
Select all the tracks and choose File>Get Info. Re-enter the correct information for Album, Artist, and especially Album Artist. Click on the sorting tab and delete anything in all fields.  Click on the Options tab and set 'Part of a compilation' to 'No'. Click 'OK' and see what you got.