Finding common column values with duplicate numbers

Hi
i have two columns where in i have a field Region ID coming from two diff tables. Now i need to find out the common Region ID values between Table 1 and Table 2. InTable 2, i have duplicate Region ID's. How can i find out the common values between the two columns with duplicate values also.

I have attached the file with the values.

Pls help me what can i do.

Thanks
Rita