Inner Join Matches Non-equal Fields??????

Hi group,

This morning we had an issue with a simple join between 2 tables e.g. table1 and table2.
Both tables have 1 column called 'fielda' with datatype varchar.

Let's assume the following values:
Table1:
hello
Hello

Table2:
hello

This statement joins the tables:
select a.fielda
from table1 a inner join table2 b on a.fielda = b.fielda


It returns:
hello
Hello

????????????????????????????????????????????????????????
What the $#@#$
Why doesn't it return 1 value:
hello


Any ideas?
The outcome is exactly what we want but I would expected to have to use the following:
select a.fielda

from table1 a inner join table2 b on UPPER(a.fielda) = UPPER(b.fielda)

What if I wanted to return all EXACT matches? Then what? Change collation?