In this paper, we propose UniBAS(Unified Bug Analysis System) to provide a unified repository model by integrating the extracted data from the heterogeneous bug tracking systems. The UniBAS reduces the cost and complexity of the MSR(Mining Software Repositories) research process and enables the researchers to focus on their logics rather than the tedious and repeated works such as extracting repositories, processing data and building analysis models. Additionally, the system not only extracts the data but also automatically generates database tables, views and stored procedures which are required for the researchers to perform query-based analysis easily. It can also generate various types of exported files for utilizing external analysis tools or managing research data. A case study of detecting duplicate bug reports from the Firfox project of the Mozilla site has been performed based on the UniBAS in order to evaluate the usefulness of the system. The results of the experiments with various algorithms of natural language processing and flexible querying to the automatically extracted data also showed the effectiveness of the proposed system.