If Salaried employee of IT Company also earns addl. income as Visiting Faculty, double taxation?

Let's say, a Salaried employee of IT Company earns Income_A in his regular job. Let's say he also earns additional income as Visiting Faculty (say, Income_B) in a one time stint. The remuneration from the Visiting Faculty stint would be subjected to TDS of 7.5% currently. My question is what happens when Filing is done next year? There would be 2 Form16s (one from regular job at IT company & another pertaining to Visiting Faculty income)? And, guessing that the total income from these sources needs to be calculated & the appropriate Tax Slabs applied. Would Income_B be taxed again? Even if this is not a case of double taxation, would Income_B counted under a higher income tax slab rate than the TDS rate? (Assuming Income_A itself places the person in high tax slabs)