Creating a custom field with the exact same name and type is possible. So if there are filters searching for "Team" and there are suddenly two custom fields with the name "Team", the query doesn't work anymore.
You then have to alter the query, so that not "Team", but the internal ID of the correct "Team"-field is used (which isn't really feasible when dozens of queries are in use).
Is there a useful reason for this "feature"?