[SQL queries run twice in JasperServer]

Hello,

The problem i'm facing is that when I run a report including "Table element" in JasperServer, I see in the logs the SQL query run twice :

2015-01-14 11:19:21,909 DEBUG JRJdbcQueryExecuter,pool-4-thread-86:254 - SQL query string: SELECT * FROM table;[/code]

2015-01-14 11:19:26,091 DEBUG JRJdbcQueryExecuter,myreport subreports #1:254 - SQL query string: SELECT * FROM table;[/code]

Please, could someone tell me what each query stands for, and how to make it run once only ?

Edit : this problem doesn't occur when I placed fields in "details group" instead of using a table.

Best regards.