Hello Jignesh,
You can use the standard AX filters to identify "duplicate" customers. What I cannot take from your question is what you understand under a duplicate customer (same name, same location, ...) and what you plan to do with the duplicate record. If you want to know more on how to deal with duplicate records please search for Andres posts on this forum as he already contributed a lot on this topic. I am pretty sure that you will find some good input on how to deal with those records.
All the best for you,
Ludwig