In this passage we learn about Abraham's second family after Sarah. They all do alright becoming the fathers of nations. Gen. 25:1-4. Ishmael comes back to bury Abraham in the tomb that Abraham bought from the Hittites for Sarah. So, that is kind of sweet. We learn that Ishmael's descendants also form twelve tribes Gen. 15:12-18.
Then we get another story of two sons. This time from the same womb. Spoiler alert: the first son is not the favorite. Then, we get this reboot of the my-wife-is-my-sister trope. Gen. 26. In fact, this time, it is with one of the kings that Abraham did this to, Abimelek. Cf. Gen. 20. Also, the whole reason Isaac has taken the crew there is out of hunger.
So, with both the Philistines and the Egyptians we have stories of the patriarchs going to the country, being somewhat deceptive with them, and at least with the Philistines, living together for some time after that in mutual harmony. This, to me, is an interesting theme to have repeated in our sacred stories. As is the theme of the oldest son not being the most favored son. Did the Hebrews have an inferiority complex?