An interesting story happened to me flying internationally with BA to Heathrow, I wonder how frequently this happen.

Backstory: When I arrived at the airport's check-in, I was told that I was already issued a paper boarding pass and checked one bag which I obviously didn't. After much waiting at the check in desk, the staff issued me a boarding pass and checked in my two bags. When I tried to enter the passport control and security area, the airport security stopped me from going through as they said someone else with my name already entered. BA check-in agent then escorted me and waved me through and all was good so far. Then when I tried to access the lounge, I was denied access saying I already entered the lounge which truly puzzled me. Once onboard in CW, the cabin manager approached me saying someone else is sitting here and I need to check my boarding pass to find my correct seat. Again after much back and forth, I realised that the other person was issued a boarding pass with my name/BAEC number/ eticket and had one checked bag with my name on it (the person has different name/nationality, with no similarities with me), in total there were three bags checked in under my booking. How this person was allowed to board using different passport/name is beyond me.

I find this to be a serious breach of security/person information caused by the ground staff at the airport. What you think?