Alan went to the supermarket. He found the cashier a familiar face.
Could he say?
You look familiar. Where did I see you before?
You look familiar. Have I seen you before?
You look familiar. Where have I met you before?
In my country teachers would say that the most suitable option is Present Perfect.
That, of course, doesn't mean that Past Simple is wrong. = but they wouldn't advise us to use it that way.
Sometimes I get tired when teachers use an excuse that "you wouldn't hear that from native speaker".
I think I shouldn't use the word "excuse". It's more like it's the easiest answer for them, cosidering that maybe some of them have never really talked with native speakers and this answer is just a way to get out of this question very quickly.
That doesn't mean that I hate my teachers. I hope it didn't sound like that.
Thanks for the comprehensive reply.
You look familiar. Do I know you?
You look familiar. Have we met before?
You look familiar. Where do I know you from?
You look familiar. Where have we met?
You look familiar but I can't work out where from.
You look familiar but I can't place you.
You look familiar. Do you recognise me?
Those would be my suggestions.
As far as the teachers' excuse about native speakers is concerned, I would agree that if your teacher is not a native speaker or does not have an absolutely native level of English as a second language, they really shouldn't say with any authority "you wouldn't hear that from a native speaker".