How to use custom field type in mappings to achieve multiple type mappings within an index?

Could you provide a full recreation script as described in About the Elasticsearch category. It will help to better understand what you are doing. Please, try to keep the example as simple as possible.

A full reproduction script will help readers to understand, reproduce and if needed fix your problem. It will also most likely help to get a faster answer.

So provide a typical example of your 2 types.