Any issues if I join another company till I get the joining letter from TCS?

I'm a fresher who got offer from TCS after passing the NQT and interviews. I accepted the offer letter from TCS in July but haven't received the joining letter yet. I'm not sure when I'll get it and have decided to join another company. It has a probation period of 6 months. I wanted to know if there will be any problems when I join TCS regarding BGV? I'm sure that the other company will give me all the related documents like relieving letter during the probation period.