A name collision is
|“||an attempt to resolve a name that is utilised in a private name space (e.g. non-delegated Top Level Domain, or a short, unqualified name), resulting in a DNS query to the public DNS, and a matching name can be retrieved. In most cases, the cause is a misconfiguration and disregards ICANN recommendations.||”|
"Name collision occurrences are not new and have historically been observed and reported as queries containing non-delegated TLDs at the root level of the DNS. They have received renewed attention because many applied for new TLD strings that are identical to name space labels used in private networks."