@acenu can you look at this question

Since you use this plug in you might have an answer... if not that is ok...
https://premium.wpmudev.org/forums/topic/does-anyone-know-of-a-way-to-not-allow-duplicate-siteblog-names-within-a-network-of-networks#post-427313
sorry I had to post this as a new item because the way the queue works here seems to make older posts fall off the edge of the earth for a while, especially if I add info + it may be that once one staff member grabs a ticket, others do not have it on their queues