There was even a publicity shot in which Lavigne had "Melissa" written on her hand.
And so far, the obsessed fan's theory has got everyone talking.
"She was born in ontario, canada in 1984 and her first album "let go" was released in 2002 when she was 18", Givenchyass explained, adding "up until this point she was so used to being able to live a normal life and now that she was famous, she couldn't handle the paparazzi so she chose to hire a look alike to walk around LA for her and pose for the paparazzi".
She then, supposedly, hired a convincing body double to pose as her at public appearances.
An astonishing theory came to light two years ago, speculating the Complicated singer committed suicide in 2003, following the death of her granddad.
They claim the "Sk8er Boi" singer became severely depressed after her grandfather's death.
However a third lashed out at the freaky notion, adding: "Not hating on anyone but honestly everyone has to get over "Avril died and this is Melissa" like wtf".
Twitter has been going wild since the theory reemerged.
"... It wasn't fake It happened, you passed by No you are gone, now you are gone There you go, there you go Somewhere I can't bring you back".
Exhibit B: While wearing heavy makeup, Avril and Melissa's mostly-identical eye shape looks a l'il different.. One Twitter account (minus the official check mark) claiming to be Vandella has her alleged name spelled incorrectly in its bio.
Some users are definitely seeing the amusing side.
While you can read all about the theory in a variety of places, it's harder to find is information about Vandella, starting with whether or not she actually exists as a real person.
The blog was created to "demonstrate how easy it is to launch a great online conspiracy theory", according to BuzzFeed journalist Ryan Broderick, whose blog reference in 2015 accidentally revived rumors.
Even when the singer tweeted her mum to wish her "Happy mother's day", yesterday the responses from fans included: "Happy Mother's Day, Melissa" and "Melissa, it's OK".
In March this year she announced she has moved record labels to BMG. It's an album full of subliminal messages apparently left by the "New Avril".