Hi Anirudh,
I assume you have 2 different indexes and applied to the same search web part (or your search parameters in code).
Please be careful if all your indexes are using with stemming or not at analyser selection (can only all having or all without it).
You cannot search both index together when "content" index without stemming while another one "calendar" with steaming. Otherwise, search results will only apply to the first index which can provide results.
(In Multiple, A1 and A2 indexes with stemming while B1, B2, and B3 indexes without stemming)
If the first index which can provide result is A2, you will only see the results from A1 and A2. On the other hand, it will become results in B1, B2 and B3 only.