Additional margins on positions resulting in net-off of physical delivery obligations

I have written ITM put and written ITM call, (both the positions result in net-off of physical delivery obligation), does zerodha collect additional margins in last two days of expiry

Margins in general go up during the last two days of expiry, and as a result margin requirement will increase even if your position is resulting in net-off.

Eg. You have Reliance 2100 CE Short and 2500 PE Short, and your margin requirement is 454k and you are getting a margin benefit of 350k

On the last two days of expiry, the margin requirement for 2100 CE Short will increase to twice of the current requirement of 413k to 826k while the margin for 2500 PE will increase from 392k to 784k, factoring in the 350k margin benefit your margin requirement on last two days of expiry will be 1,260,000 (826k + 784k - 350k)

Subham ji , here my both positions are resulting in net-off of any delivery obligation, then why should
there be any additional collection of margins; Are my existing margins on both the short positions not
sufficient for the risk involved?

As margin requirements in general go up during last two days of expiry, even if your position is resulting in net-off, the margin requirements increase.