UDF + ORDER BY returns twice the value in view

--replace_result $UDF_EXAMPLE_SO UDF_EXAMPLE_LIB

eval CREATE FUNCTION udf_sequence RETURNS INTEGER SONAME "$UDF_EXAMPLE_SO";

CREATE TABLE t1 (a INT);

INSERT INTO t1 VALUES (4),(3),(2),(1);

SELECT udf_sequence() AS seq FROM t1 ORDER BY seq ;

CREATE VIEW v1 as SELECT udf_sequence() AS seq FROM t1 ORDER BY seq ;

SELECT * FROM v1;

DROP VIEW v1;

DROP FUNCTION udf_sequence;

DROP TABLE t1;

seq

2

4

6

8

seq

1

2

3

4