1. I’m going to out with some friends coming next weekend.
2. I’m going to go out with some friends coming next weekend.
I reckon I don't need to put anymore "go" when we use "going to". That's why, it seems to me that No. 1 is correct.
Thanks again.
Thank you for your corrections!
2. I’m going to go out with some friends coming next weekend.
I woud say: I'm going to out with some friends this coming weekend. (definitely no "to" !)