Reading the article, I imagined what the people (?) on those planets must think when they discover they're not alone.

Let's say we discover we are not alone. We know those aliens must not be from our galaxy, so do we push for development of faster-than-light travel? If so, why? Intelectual curiousity, defense, offense, trade, habitation?

As for the hypothetical galaxy with two planets of life: Are they developing the same? If not, do they, and if so why, expand to the other? If they are, are they afraid of each other? Do they have a "cold war"? The possibilities are endless.

Like Firefly, there are many posibilities for great sci-fi.

I got to the bit about 2 earths circling each other and instantly thought of the Fire/water planets that exist on the opposite side of the sun to earth which is why we didn't know they exist, from the TV show Lexx (season 4, worst season ever)