I think this happens if you have breakpoints on lines, and then delete the text with the breakpoint assigned. Just go to the Breakpoints list and delete all the duplicate breakpoints to remove them.
I’ll file a bug at our end to try and improve the handling of text deletion to ensure duplicate breakpoints are removed in the future.
If it’s any help, it happened again, this time I cut text with a breakpoint from one handler to create a new handler and all the duplicates were to the same line in the new handler.