I got 2 offers one is TCS and the other one from TechM. While TechM provides 1.5L higher as per tcs. I have 11 yrs exp. Which one is better?

It's depends open location role.As you mentioned you have 11 years of experience I am sure your coming in 30 % salary income tax.so your in hand will not change with a big difference.so ignore that salary part .now check what role your getting in both if in TCS it's C3B it's good 👍.for tech Mahindra work wise it's good but you need to handle more things which are also not part of your role.so think about this and join TCS only if you set your mind my salary growth will be 5 % each year only not more than that.

I am wondering how , if you are not a part of tcs how come your profile is appearing in grapevine tcs section saying you are already part of tcs.

Consider TCS as your retirement company, spend 2 to 4 years other companies increase your CTC finally join and settle with TCS.