Problem in alv output

Hi All,

For one my reports i used alv grid display as output.

Correct output is coming but the problem is when i press the refresh button the output valus getting duplicated.

For eg :

My output before i press refresh button is

A B C

25 abc xyz

When i press the refresh button the output is changes to

A B C

25 abc xyz

25 abc xyz

here new line added with same entries when i press refresh.I f i again press refresh then one more line added with same entries.

Please let me know what is the problem and suggest me the solution for this.

Thanks a lot.