Hello Applicant,

Yes, you can. It is not mandatory to write both the exams (i.e both January and April).

This means it would be optional for the candidate to appear once or twice for the current academic session. In case a candidate appears in both the tests, the better of the two scores will be used for the admissions and eligibility for JEE (Advanced)-2019 they have attempted both the examinations, best of the scores would be taken for the merit list.

Hope this helps.