At the moment you can create multiple fields of the same name within the table. This might be changed in the future.
The property lookup API endpoint would only return 1 or no results and property names should not be reused. Each property is linked to a type and a unit of measurement, both of which uniquely identify a single type and a single unit of measurement and preferably names will be sufficiently descriptive to reflect that.
Please note that property management API are not to intended to be used by application developers -- applications are meant to choose from properties, types and units of measurement provided for them to encourage consistency across the HAT ecosystem.
I have noticed an issue with property lookup endpoints are only enabled for the owner account and will report that to the team.