Query Returns Duplicated Values For Some Cells

I'm trying to execute a query which is looking at data from 2 different tables and most of the data fields in the tables are the same. For instance table 1 has Dept, Res, Period_date, & Available Hrs and table 2 has Dept, Res, Period_date, Project & Forecast Hrs. The results I'm looking for are as follows:

Dept Res Period_date Project Forecast Hrs Available Hrs
11 A 11-02-07 123 XXXXX
11 A 11-02-07 456 XXXXX
11 A 11-02-07 789 XXXXX
11 A 11-02-07 012 XXXXX
11 A 11-02-07 XXXXX

But the "Available Hours" are duplicated in the preceeding 4 rows.
Thanks for any advice on this.