Dennis
Try this modified report, basically what is happening is as follows.
When one or more items in the report are deemed the same, only 1 is displayed and its Quantity is incremented to reflect the number of items. So in you report you need to multiply the Pattern Length by Item Quantity. Ive added Quantity to the report, set its column width to 0 (so it does not display) and put a calc on the Length field (Pattern Length * Quantity).
Another option would be to use the Pattern Centre Line Length field, using this field give you the option to display the value "per Item Qty" or "total Item (Extn)" in the contents tab. Setting it to the latter will automatically multiply out the lengths by the quantity.
Andy