TB 18.104.22.168 running in free trial mode with Pro privileges (at least for now):
In the Instant Search box (lower left corner) I enter the name of a thought that doesn't exist in my brain. I'm presented with a selection of thoughts, an option to create a new thought, and an option to search the brain. After select "Create", I find that I immediately have 6 copies of the new thought in my brain. I must have a preferences setting wrong.
P.S., This brain was newly created with TB 22.214.171.124 and J-1.7.0_67 just a few days ago.