Creating multiple instances of a model

The first example is never a good idea. If a model is already loaded, it will not load again.
The second example isn't a good idea either. It makes your code unnecessarily complex.

Please, explain what you are trying to do. It appears to me that you want to fetch a list of customers from your database, is that correct?

Yes, that's correct.  But each customer should be an object/model with access to the relevant class functions.