Hello Swathy,
You can use same masking job. My question was, are you trying to mask table second time, which was already masked first time, OR you have unmasked data in table, which you tried to mask using same job?
Could you please help with details of Segmented Mapping algorithm(Segments, Range etc) you created and what type of column you trying to mask using that algorithm?
For troubleshooting purposes, you can also try to remove unique constraint from the column and tried to mask it. After masking, check out the masked values which violate the unique constraint. This will be helpful to understand, which unmasked values are getting masked to same value.
Just wondering, if it works first time for same data, it should work again. Please also check, if you get any new data in table, which is getting masked to same value.
Thanks