Double entry validation is simply having the data entered twoce into two different tables and then comparing the two tables for equality. You can simply use two data intput tables in addition to teh master table that ultimately holds the data. Two users enter the same data in one of the tables. When they are completed you compare the tables to each other and the records that match are saved to teh amster table. The match failures are reported on a exception report and the users have a mechanism to fix the errors and rerun the comparison.