[AccessD] UNION query bug?

I thought that a union query (Access 97) combines the results of 2 or more queries  For example:

qryC = SELECT * FROM qryA UNION SELECT * FROM qryB;

qryA contains 1 row and qryB contains 1 row.  qryC should always produce 2 rows??

qryA contains 3 fields (Purchase Order#, Cost Acct#, Amount) from tblA
qryB contains the same 3 fields (Purchase Order#, Cost Acct#, Amount) from tblB

If the data is the same in qryA and qryB, qryC contains only 1 row.

If this is not a bug, how do I force qryC to produce 2 rows?  In my situation, qryA contains information about per diem costs and qryB contains information about bonuses, mobilization/demob costs, etc.  I need to sum these costs.  This is usually not a problem since the amounts are usually different

Thanks,
Barb Ryan