You can to detect if its a starting word by adding a

(\d\d?\d?)-\1

not sure if it solves your problem

how about this ?

^.+~_(\u+)+(\u+.)

you could use this .. (you make need to replace the “~_” with indesign’s flyout em dash [pressing the @ thing] )

^.+(?=~_)

Just make sure you use of Em dash is unique to the dates..