Getting the prompt - Another meeting overlaps with this event, How do I fix this?

The prompt "Another meeting overlaps with this event", means that there is another meeting already schedule for that slot. By default you cannot double book on TheraPlatform's calendar, however if you need to double book, you can toggle the Double Booking settings by clicking on the blue gear icon above your calendar and scrolling down until you see Allow Double Booking -- you'll then be able to turn it on or off depending on what you want to do. Save changes to confirm the settings change.

Note: If you want to only overlap events (allow double booking) as a one time occasion, allow double booking, save changes and then go back to the gear to disable it again.