Possible BUG in LOCAL SQL UNION clause

Hi All,
I wonder if anybody has noticed that, but it seems that the UNION clause
in local SQL implicitly retrieves only DISTINCT rows (D2, Paradox tables,
BDE 3.5f),
while nothing in the documentation implies that.
Example:  table TAB with two integer fields A,B populated with two exactly
same records
record 1: A=1,B=0 ;record 2: A=1,B=0.
"select TAB.A from TAB where TAB.B<>0
select TAB.A from TAB where TAB.B=0"
retrieves only one row.
Anybody knows why?
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