How to make the fnFilter is not based on the results of the last filter

this bothers me a lot of time. i use fnFilter to filter the specific column. but when i use fnFilter at the second time, the filter string of last filter also in the aoData. how can i get an aoData without the information of last filter? thanks a lot
here is my aoData:
first filter:
{"name":"sSearch_8","value":"FilterString_one"},
{"name":"bRegex_8","value":false},
{"name":"bSearchable_8","value":true},
{"name":"sSearch_9","value":""},
{"name":"bRegex_9","value":true},
{"name":"bSearchable_9","value":true},

second filter:
{"name":"sSearch_8","value":"FilterString_one"},
{"name":"bRegex_8","value":false},
{"name":"bSearchable_8","value":true},
{"name":"sSearch_9","value":"FilterString_two"},
{"name":"bRegex_9","value":false},
{"name":"bSearchable_9","value":true},