Rolf,
this bug alive inside the code that builds the plan of execution.

If there is no WHERE the optimizer is wrong to build the JOIN condition "AND "
(it seems only uses the first one ?)
A workaround becomes very simple, add a WHERE .T.

CLEAR

*	SET COLLATE TO "DUTCH"
*	SET COLLATE TO "GERMAN"
*	...

* condition 1 : COLLATE not MACHINE
	SET COLLATE TO "GENERAL"

* condition 2 : SET DELETED() ON
SET DELETED ON

*-- Create Tables and Index
CREATE TABLE table1 (field1 C(1), field2 C(1))
INSERT INTO table1 (field1,field2) VALUES("A","1")
INSERT INTO table1 (field1,field2) VALUES("A","2")
INSERT INTO table1 (field1,field2) VALUES("A","3")

* condition 3 : first table can optimize WHERE DELETED()

*INDEX ON field1 FOR NOT DELETED() TAG FIELD1_1

INDEX ON DELETED() TAG deleted1 && BINARY

CREATE TABLE table2 (field1 C(1), field2 C(1))
INSERT INTO table2 (field1,field2) VALUES("A","1")
INSERT INTO table2 (field1,field2) VALUES("B","1")

* condition 4 : SECOND table can optimize  WHERE DELETED()

INDEX ON DELETED() TAG deleted2 BINARY

SYS(3054,11)

* condition 5 : none WHERE clause

*-- Expected recordCount = 1 ; result recordCount = 3  *** USES ONLY table1.field1=table2.field1
SELECT COUNT(*) recordCount FROM table1 INNER JOIN table2 ON ;
table1.field1=table2.field1 AND table1.field2=table2.field2

?
? "LOOK THE PARTIAL !!!!"
* WORKAROUND
SELECT COUNT(*) recordCount FROM table1 INNER JOIN table2 ON ;
table1.field1=table2.field1 AND table1.field2=table2.field2;
WHERE .T.

*-- Expected recordCount = 1 ; result recordCount = 2  *** USES ONLY table1.field2=table2.field2
SELECT COUNT(*) recordCount FROM table1 INNER JOIN table2 ON ;
table1.field2=table2.field2 AND table1.field1=table2.field1

?
? "LOOK THE PARTIAL !!!!"
* WORKAROUND
SELECT COUNT(*) recordCount FROM table1 INNER JOIN table2 ON ;
table1.field2=table2.field2 AND table1.field1=table2.field1;
WHERE .T.