I ever seen X I've ever seen: Qual é a diferença?

Hey Guys

I ever seen X I've ever seen

Vi em uma musica da banda AC/DC, que estava escrito
(I ever seen), e não apenas um site de musica.

Musica: You Shook Me All Night Long

Vagalume

She was a fast machine,
She kept the motor clean,
Was the best damn woman that I ever seen,

Letras

She was a fast machine
She kept her motor clean
She was the best damn woman that I ever seen

Esta correto posso escrever assim?
Obrigado desde ja.