2 players currently have the same IGN while having different UUIDs

https://namemc.com/u/Self
2 players changed their name at the exact same time and currently have the same username, Self. Not sure if this is intended behavior, but I believe it isn't. If i am right, they were only able to submit the name because up until 5 seconds earlier nobody had it.
UUIDs:
53272003-cb43-4e78-8723-cd15c9997aa6
93954970-eb45-4124-82f1-32b8c6cf372e
Both switched username at 2:10:51 PM (UTC-5) on 5/11/2015 to the name Self.