it sounds that you indeed have no reason to duplicate the data, therefore doing it would be a mistake. Not only it’s unnecessary and it would waste database space, but more importantly you would have to add extra code to maintain the data in sync (otherwise you would end up with inconsistent database).
The right solution is adding InventTable data source to the form and either join it or link it to your data source. Also note that you’re table will need a relation to InventTable.