More then 1 H1B Extension possible while working in USA

Currently working in USA

My current employer is going to file my H1B extension in some days.

I got another offer from other employer. Other employer asking to submit all H1B documents, so they can file for my extension and Amendment.

My Question is :-

Is it possible to file H1B extension from two different employer?

If Yes, Which one I should be following ? What ever comes first?