Audio Evidence
Listen to the vocal comparison.

The same word "go" the same note "E5"
TWO perfectly different voices!

Samples from:

"Your Mother Should Know" (first "go" by James Paul McCartney)
"Hello, Goodbye" (second "go" by Faul)

both from Magical Mystery Tour Album

Paul McCartney - Billy Shepherd voice spectrum comparison
On the left - James Paul McCartney Voice spectrum - On the right - Billy Shepherd voice spectrum -

The list of "Sgt.Pepper" Album is:

Sgt. Pepper's Lonely Hearts Club Band : performed by Faul
Getting Better : the intro performed by Faul
When I'm Sixty-Four : the first song performed by the "imitator"
Fixing a Hole : performed by the "imitator"
She's Leaving Home :the last complete song performed by James Paul McCartney (that's why George is pointing this song in the back cover of the Album)
Lovely Rita : performed by the "imitator"
A Day in the Life : the central insert is performed by James Paul McCartney
Probably "A Little Help From My Friends" is performed by Faul imitating Ringo's voice !!!

The list of the "Magical Mystery Tour" is:

Magical Mystery Tour : solo part performed by Faul The Fool On The Hill : performed by the "imitator"
Your Mother Should Know : We can consider it the last song performed by James Paul McCartney but originally was only a "take" reassembled by George Martin repeating it X times
Hello, Goodbye : the first song performed by Faul (imitating Paul's voice)
Penny Lane : this song was performed originally by James Paul McCartney but he left it incomplete.
The "imitator" overdubbed Paul's voice filling the left pieces
We can listen the original voice of James Paul McCartney alone in the verses "very strange"

The list of the "White Album" is:

Back in the U.S.S.R. : still under check (it's difficult because the voice is heavily filtered) but, if the compilation 1967-1970 contains only the songs performed by the "imitator" and those performed by Faul, it could be performed by the "imitator"
Ob-La-Di, Ob-La-Da: performed by Faul
Martha My Dear: performed by the "imitator"
Blackbird : performed by the "imitator" (imitation masterpiece)
Rocky Raccoon : performed by Faul
I Will : performed by Faul
Mother Nature's Son: performed by the "imitator"

From "Abbey Road":

All "Paul voice" songs performed by Faul except "Golden Slumbers"
Her Majesty: performed by James Paul McCartney