Overlap
Overlap occurs when two or more batches use one resource simultaneously. A warning message is displayed related to overlapping of batches if you run Check schedule. You can eliminate overlaps by using schedule batches or allocate.
You must clear the check schedule check box in the Resource Group Entry window if you do not require to view a warning message related to overlap. You must also, clear the Check Overlap check box on the Check schedule tab of the Preferences window. In the Preferences window, you can specify to check overlap in just process resource groups or just tank resource groups.