Nonrecoverable tax lines created for freight

We recently upgraded to R12.2.5.  For our US Org, we turned of the auto calculation of tax on the AP workbench. When creating PO invoices, we have item lines generated from the PO.  AP then manually enter freight and tax from the invoice in that order. When looking at the AP distributions on the tax line, there are 2 distribution lines.  One line amount with Type of Tax Rate Variance (TRV) and another for Type of Nonrecoverable Tax. It looks like the TRV line is the tax amount for the item line, and the Nonrecoverable Tax line is the system