Creating a relationship between one field in a table with two fields in another Is the picture below the only way to create the relationship described in the title with referential integrity? Why does Access not allow me to do this without the "duplicate" table? Thanks!
The only reason I see this occurring is if you wrote a query that INNER JOINs twice

EXAMPLE

SELECT tblState.*,tbl_Estimate.JobSiteCity,tbl_Estimate1.JobSiteZip
FROM tblState
INNER JOIN tbl_Estimate
ON tblState.ID = tbl_Estimate.JobSiteStateID
INNER JOIN tbl_Estimate AS tbl_Estimate1
ON tblState.ID = tbl_Estimate1.JobSiteStateID;


Because you are running INNER JOIN twice, the graphical representation has to match. This would indicate the possibility of checking different columns with each INNER JOIN

Let's say you are checking for Jersey City but didn't specify the state.

SELECT DISTINCT tblState.*,tbl_Estimate.JobSiteCity,tbl_Estimate1.JobSiteZip
FROM tblState
INNER JOIN tbl_Estimate
ON tblState.ID = tbl_Estimate.JobSiteStateID
AND tbl_Estimate.JobSiteCity = "Jersey City"
INNER JOIN tbl_Estimate AS tbl_Estimate1
ON tblState.ID = tbl_Estimate1.JobSiteStateID;


This should return JobSites in all ZipCodes from Jersey City, NJ and Jersey City, WI

If you collapse the query to

SELECT DISTINCT tblState.*,tbl_Estimate.JobSiteCity,tbl_Estimate.JobSiteZip
FROM tblState
INNER JOIN tbl_Estimate
ON tblState.ID = tbl_Estimate.JobSiteStateID
AND tbl_Estimate.JobSiteCity = "Jersey City"


you should get the same result, but the picture should only have tbl_Estimate once