You can combine columns from both tables using (id, name) as join criteria with:
select a.id as id, a.name as name, a.somefield1 || ' ' || b.somefied1 as somefield1 from tablea a, tableb b where a.id = b.id and a.name = b.name and b.name = 'mooseburgers';
If you want to join only (id) and combine the name and somefield1 columns:
select a.id as id, a.name || ' ' || b.name as name, a.somefield1 || ' ' || b.somefied1 as somefield1 from tablea a, tableb b where a.id = b.id and b.name = 'mooseburgers';
Although I must admit that this is a rather unusual way of doing things. I assume you have your reasons :-)
If I misunderstood your question and you just need a more traditional join of the two tables, use something like:
select id, name, somefield1, '' as somefield2 from tablea where name = 'mooseburgers' union all select id, name, somefield1, somefield2 from tableb where name = 'mooseburgers'
This will not concatenate the rows, but instead just add the rows from the two queries. Use union yourself if you want to remove duplicate rows, but if you are sure that there are no duplicates or you do not want to delete them, union all often more efficient.
Based on your edit, the actual query will look like this:
select name, somefield1 from tablea where name = 'zoot' union all select name, somefield1 from tableb where name = 'zoot'
(or union if you do not want to duplicate, where a.name==b.name=='zoot' and a.somefield1==b.somefield1 ).