[ceejayoz]

> There were two of them next to each other. Is that common at all?

https://en.wikipedia.org/wiki/Formation_flying

That you're asking that question really makes it hard to credit the claim that you successfully ruled out "all the logical possibilities".

edit: You edited in some additional, so:

> Does 'formation flying' involve craft flying around in random non-linear fashion?

https://en.wikipedia.org/wiki/Dogfight

A distantly seen dogfight at night would involve afterburners (bright lights! and they'd wink on/off during maneuvering, when they're turned on/off, or when the plane turns to face towards you instead of away from you) and rapid random non-linear movements as described.

[ozzmotik]

my only question is, how likely is it that anyone is going to actually be witness to a dogfight at any given time? seems like something that would be pretty rare.

[ceejayoz]

Depends where you're located. I don't have an aviation map handy, but Beale AFB is less than 200 miles south of Mt. Shasta, and the Air Force trains continually.