After you have given the letter to Kanie you get a Tinpet. There is a way to get the second one. After the air Medabot takes you back upstream read the sign near where you fell in the river. Tell him you want to go downstream. Go to Kanie's house. Talk to her to get $1 for the $1 you used coming to see her. Talk to the Medabot in her house. Open the other box.