By default, IAConnect merges PO lines that have the same PO line number, project, account, and org. Non-PO lines are not merged. To disable the merging of PO lines, add the following element to the appSettings section of the web.config file:
<add key="DisablePOVoucherLineMerge" value="true" />
If this node already exists, make sure the value is set to true to disable the line merge. In a default installation, the value is set to false.