ORA-02275: such a referential constraint already exists in the table

SQL> create table test1(id number, name varchar2(30));

Table created.

SQL> create table test2(id number, age number);

Table created.

SQL> alter table test1 add constraint pk_test1 primary key(id);

Table altered.

SQL> alter table test2 add(constraint fk_test2_test1 foreign key(id) references test1(id));

Table altered.

SQL> alter table test2 add(constraint fk2_test2_test1 foreign key(id) references test1(id));

alter table test2 add(constraint fk2_test2_test1 foreign key(id) references test1(id))

*

ERROR at line 1:

ORA-02275: such a referential constraint already exists in the table

SELECT c.owner,

a.table_name,

a.column_name,

a.constraint_name,

C.R_CONSTRAINT_NAME

FROM ALL_CONS_COLUMNS A, ALL_CONSTRAINTS C

where A.CONSTRAINT_NAME = C.CONSTRAINT_NAME

and C.CONSTRAINT_TYPE = 'R'

and C.TABLE_NAME='TEST2';

So you can see the referential constraint already exists.