Joining new job without resignation being accepted

No probably not, though you will or may be declared Absconded in your previous employment and your previous employer reserves all the right to secure the handover of the duty or operational activities under the intervention of Court if you escape without proper handover.

The case may be that employee is in payrolls of two companies for some days,although not paid by one.Will that count as double employment?

Then naturally it will be considered as double employment.

Can second employer terminate the employee on this ground even though he has not received salary from first one after absconding after resigning ?