Second masters would give your brownie points in the interview , All IIMs are looking for diversity in the class , in the recent class of IIM A B C , it is seen that there are always students have double masters ( though the number is single digit ) . 

Since you have psychology masters , it increasess your chances for admission , as u come in the  " special category " and there are only few people applying for MBA after psyhcology , 

All the best for the CAT exam ! go for the kill !

There might be questions related to it during the interviews but as far as I know this won't affect your composite score and in turn won't affect your probability of getting calls. All the best!