Hi Jaydip,
Thanks for your help on this...but I just Investigated and go the root cause of the problem.
There are 4 plants belonging to GB country that were assigned to the Sales Org/DC combination and along with these there was one plant that belonged to US that was assigned to the same Sales Org/DC combination. This was where the issue had originated from. Because of this assignment the 2nd Tax Classification line was appearing.
Nagesh.