"Is the 10k / 5k double common in conference?"
I can tell you that at the Heptagonals (Ivy League championship) meet, the top four guys (and a few others) from the 10,000 came back the next day, though one did the steeplechase rather than the 5,000.
And this was the case, even though only one out of the top four was from a squad that had any chance of winning the overall team title, and the 10,000 had been run at an honest pace (a guy ran sub-30:00 and didn't score) in conditions that were less than ideal.
For some schools--certainly all the Ivy schools--conference matters hugely, and they'll pull out all the stops to try to win...or just to have their team finish in the top half of the league, or earn bragging rights over a traditional rival.
My observation is that some teams do simulate this situation in practice once or twice, with a couple of hard days back to back; others just have their guys do two hard days of racing at one or two meets earlier in the season. Whatever they did to prepare, it seemed to work: some of the guys actually looked better in their second race than in their first.
The poster above gave one clue, though we saw that more BITD: years of mileage, if you can handle it, do make it relatively easier to recover from a hard day and bounce back. Example, Shorter at the 1972 OG: American record in the 10,000m heats, another AR three days later in the final, marathon gold a week later.
At my own, much lower competitive level in the same year, it was routine for us to run hard road races, usually ten miles or longer, on virtually a weekly basis; and I was considered not *really* serious, because my mileage rarely exceeded 70 per week.
It's mostly a question of expectation, I think. American distance runners in general seem to be getting a little more hardnosed about doing multiple races and expecting to do them well.