Examining the pairs: 1. Allahabad Bank - Kolkata: Correctly matched. Allahabad Bank's headquarters was in Kolkata until its merger. 2. Small Industrial Development Bank of India (SIDBI) - Mumbai: Incorrectly matched. SIDBI's headquarters is in Lucknow. 3. The Overseas Bank (Indian Overseas Bank) - Chennai: Correctly matched. Indian Overseas Bank's headquarters is in Chennai. The question asks for the pair that is not correctly matched. Only pair 2 is incorrectly matched.