Issues with Multileg order

I'm facing 2 issues -

1. I'm not seeing the margin benefit applied when placing multileg order
   For example 6 lots of BankNifty options should require ~1.2L margin but it is calculating as per unhedged selling - which is 6.5L

   

2. What does this error mean?
   Both legs are of same instrument (NIFTY) and same expiry (18 July) and both are PE. One is sell and other is buy