putting data into table names (HeadOfficeOne, HeadOfficeTwo), is a no-no in
database design, just as is putting data into field names.

you have a many-to-many relationship between products and head offices:  one
head office may be associated with many products, and one product may be
associated with many head offices. in a relational database model, a
many-to-many relationship is expressed with a child (linking) table that
forms the "many" side of a one-to-many relationship with each of the two
parent tables.

suggest three tables:

tblProducts (parent table)
UPC (pk)
the other fields you listed in your post. just make sure each field
describes the product itself, NOT the product in relation to an office.

tblHeadOffices (parent table)
HeadOfficeID (pk) (note:  not a good idea to use any character except alphas
and underscore in a field name, or any name, in Access)
other fields that describe a head office itself, not the office in relation
to a product.

tblOfficeProducts (child [linking] table)
OfficeProductsID (pk)
HeadOfficeID (fk from tblHeadOffices)
UPC (fk from tblProducts)
CaseCost
other fields that describe a specific product in relation to a specific
office.

if you will never have the same product listed for the same office *more
than once* in tblOfficeProducts, then you can remove the OfficeProductsID
field and use both foreign key fields as a combination primary key for the
table.

hth