Is there an easy way to find distinct records, i.e. types rather than tokens, or do I have to write a loop which throws out the duplicates?

Well, if I understand your question, this is how relational databases excel.

You can use a 'self-join' relationship to have records show on a layout when criteria (in a global field) matches. As you change the 'match' field the displayed records change.

Does that help?
If you are more precise with an example we can be more precise with answers.

Here is an example:
I have several blue cars, red cars etc. in the DB (field "color"), each car is a record. Now a script should tell me how many different colors I have, i.e. 3 if all cars are either blue, red or green, and 2 if they are either blue or red, no green cars.

There are different ways to do this, but it depends on what you mean by: