Availability Bug? Exact time slot repeated twice on single day (two 11 am slots instead of one)

I have created a booking page (and re-created it several times). 

What I want to do: offer 2-hour time slots on select days across two weeks. This is a one to many schedule setup.

When I view the finished booking page, there is one day/date when the time slot repeats twice. For example: the 11 am sign-up slot is repeated a second time on the same day. 

I've tried seemingly everything but none of my attempts to fix this are working. Is there a bug?