Actually - and please correct me if I'm wrong - it's kind of a modified group stage. Results from Stage 1 carry over and there are only 2 games for each team. Each team faces the teams they didn't play in the first group stage. E1 (likely USA) plays F2 (likely Greece) on Sept 7th and then E1 (likely USA) plays F1 (likely Brazil) on Sept 9th. E1 and E2 don't play each other again in the 2nd round. And from what I can tell from the Bracket and game schedules, they'd only play each other if both made it to the Finals.
Here is where I'm looking. And, again, please correct me if I've misread the schedules or brackets.
http://www.fiba.basketball/basketballworldcup/2019/games