past perfect needed

AnonymousI do not think past perfect is needed here because it is obvious that if you do not need to tell me that it is because I know it before

It is not necessarily so.
You did not need to tell me that because I was not interested in learning about.

ok so I am right
but that is not because I was not interested in learning about but that is because I already knew it

thanks for your answer

AnonymousI do not think past perfect is needed here

Past perfect is not correct. The comma is not correct, either.

You did not need to tell me that, because I already knew it.

But the past perfect is natural here:
You did not need to tell me that, because you had told it to me last week.

So could you explain me why in the first case it is correct and not in the second case
Where is the difference?

thanks

You did not need to tell me that, because I already knew it. The time frame in the two clauses is exactly the same. You didn't need to tell me (at time X), because I already knew it (at time X).

You did not need to tell me that, because you had told it to me last week. The time frame in the two clauses is different.
You didn't need to tell me (at time X), because you