Data Validation - have I broken Excel? It has mixed views on the

Hi - filled with enthusiasm after yesterday's Advanced Excel course with Jens, I returned to the office determined to control data entry on a particular spreadsheet.

Please note below, when I type ", I show that as the delimiter for text, and the " is not part of the text:

I have found a weakness already: on the header record for a table, if you click the down arrow, you can see the values recorded in that column. However, it won't show "PASSPORTS " (notice the space character after) as a separate value to "PASSPORTS" (no space).

And yet, if I create a SUMIFS formula summing costs where category is "PASSPORTS" it won't include records with "PASSPORTS " as being in the category. So one part of Excel thinks they are the same category and another doesn't.

Finding this out has taken considerable time, so I thought "let's create some Data Validation rules to limit data entry! However, when I create a list including "PASSPORTS", and not "PASSPORTS ", Excel allows either to be entered, ruining my validation rule.
My question is: is there a way to restrict space characters so that they are not allowed as an extra after a text string?

I hope the answer is easier to read than my question!