Table alias scope in informix SQL

Table alias scope in informix SQL

In the following example SQL
select * from (
select col
from myTable mt
inner join anotherMyTable amt on mt.id = amt.id
) as t
where
exists (select amt.colX from anotherMyTable amt where amt.id = 42)
The 'amt' alias is defined in two places. Is it correct to declare the
second table alias with the same name as the first or I should use another
name (amt2) ?
In this example I assume that both aliases are located in different scopes
so it's okay to use the same name. I use Informix DBMS.
p.s. it's an example SQL, the question is only about table alias scope.