There is only one ending for Torahiko, which you will get by being locked into his route after the camping trip (It's unfortunate the writer for Torahiko didn't include any decision making for the route). Both events on Aug 6 can raise your affection with him, with the only potential downside with the Test of Courage is that you may be defaulted to a certain event on Aug 8. Of the seven characters who have a route, Shin should be the only character whose ending is impacted by decisions made prior to being locked into his route.
You can only choose one or the other if they are on the same day. In the original Unofficial Torahiko route, the author moved certain events that Torahiko was in around so that every event involving him could be seen, at the expense of taking away player control. The only two choices you would be given are who you sit next to at the Welcoming Party, and who you spent time with at the beach.
I rearranged everything back to better fit with the rest of the routes, and even had to make flags for certain references or events. Because of this, there are slight differences later in the game depending on which event you pick on Day 6 involving Torahiko, and the choice you pick during. For the taste test, Hiroyuki can refer back to it if he enjoyed it. Whereas with the test of courage, your choice could make Nanafuse appear later in Torahiko’s route.