Tente isso, conforme o artigo http://www.dba-oracle.com/t_extract_comma_delimited_strings_oracle_sql.html:
select distinct str from
(select regexp_substr ('ABCD1234, XYZ, ABCD1234, ABCD1234C, ABCD1234, abc, abcX, 1234U, 1234', '[^, ]+',1, rownum) str
from dual
connect by level <= regexp_count ('ABCD1234, XYZ, ABCD1234, ABCD1234C, ABCD1234, abc, abcX, 1234U, 1234', '[^, ]+')) v;
Violino:http://sqlfiddle.com/#!4/c858d/5
