How to Explain Overlapping Employment Dates to Your New Employer?

Company A provided the date of exit as 23OCT2018, but before that, I joined Company B on the date of joining as 01OCT2018.

I need help correcting this situation. Company A, a big MNC, terminated my employment, and I received a termination letter. How should I address this with Company B? Please assist me with an explanation.

Everything is based on certain appropriate documents. There cannot be suppression of documents and data. Play it safe, intimate the facts, and leave the rest to the organizations concerned to deal with appropriately. That is all you can do in the circumstances explained.