The issue occurs when the counter used for naming is exhausted.
For example if a naming policy is configured as '${NAME}-{##}' this will happen after 99 objects are deployed, for a naming policy of '${NAME}-{###}' this will be after 999 objects are deployed
Resolution
VMware are aware of the issue and a feature request has been opened to support the re-use of numbers and allow a reset of the naming feature's counter.
Workaround:
To workaround the issue delete and recreate the affected naming template.
When recreating the naming template consider using a larger counter value as per the documentation the maximum length of the number property in naming templates is 19 digits.