with t as (select 'Иванов  Иван Иванович' FIO from dual union all
           select 'Пертов Перт  Петрович' FIO from dual)
select  FIO
from t
where instr(FIO,' ',1,2) - instr(FIO,' ',1,1) = 1

with TABLE_USER as (select 'Иванов  Иван Иванович' s_name, 1 objid from dual union all
           select 'Пертов Перт  Петрович' s_name, 2 objid from dual)

,temp_table as (
select (substr (s_name, instr(s_name, ' ', 1,1))) as str, s_name, objid
from TABLE_USER tt where 1=1 
and s_name like '% %' 
and (s_name not like '% ' or s_name not like '% %'))

select * from TABLE_USER tt
where 1=1 
and s_name like '% %' 
and (s_name not like '% ' or s_name not like '% %' or s_name not like ' %')
--and FA_CHILD2BUS_ORG = -2
and tt.objid not in (select tt1.objid from temp_table tt1 where 
REGEXP_LIKE ( (substr (s_name, instr(s_name, ' ', 1,1))), '\w(*)'))