Questions

I have some dreams that been the same dream in the very past
does that always happen to someone cause I keep haveing the feeling that I had that dream Before.And how long are dreams I can't tell.

I believe people refer to these dreams are "recurring dreams", I don't know what causes them, maybe they have a meaning to you?
You can use them to your advantage, for example let's say you have the same dream every week, you could train yourself to do a RC next time you experience that same dream again, and become lucid :)
Nobody can tell how long they're dreams are exactly, of course unless they are at a sleep lab with the necessary instruments. Dream time is usually same as real-life time, but sometimes we have those dreams that last "days" (inside the dream, of course)

Oh Okay Thank you.