Joining another company with delay of one month from last working day

Hi,
Actually, i had an offer from the TCS and my last working day is in this week.
Recently, i got selected for very good company but they are giving me joining after one month (because of lengthy BGC process).
Will it be worthwhile to wait for one month after resigning from previous company.
Or should i join TCS, and resign after few days (as notice period in probation period is just one month)

Joining TCS yet continuing in earlier employment is an unethical practice and is not at all endorsed. You should not entertain such thoughts and follow that path which is straight and honest. In the long run of life, one month of service won't matter really, but it should not leave guilty conscience throughout your life.

Thanks KK!HR,
I was not meaning that I will be joining TCS while serving my previous employer.
My problem is, my last working day is 09 December and my joining to TCS is on 11 December.
But I got very good offer from other company which is offering me joining after one month due to their bgc process.
So I was thinking to join TCS for one month and after that I will join other company (as TCS has only one month notice period in probation period).
So what impact it will cause on my career. Any suggestions.

Dear Sonu$,
There is a limit to being self-centered. Already you have been selected by TCS. Hope you have accepted their offer. Now disregarding acceptance of offer would leave TCS in lurch. You do not want to just stop at that but as the new company will offer employment after a month, you wanted to join TCS only to leave them after a month. This will help you in maintaining monthly cashflow!
You may do these machinations but have you thought any time what does it take to select a right candidate? Because of your selfish motive, all the efforts TCS's recruiters will go in vain!
If you leave TCS after a month, you would be ditching TCS doubly. Yes, you may do that but then please remember that life is too long and possibly someone in future may ditch you not just doubly but triply as well. That time you should not grumble.
Ethics demand joining TCS as committed to them. Nothing is as bad as reneging one's commitment. As such TCS is a big brand and there will be great opportunities to grow.
Thanks,
Dinesh Divekar