The mystery is solved!

I learned today why Trikke sends a duplicate large hex wrench. It's for changing wheels. I recently was talking to someone on the street about the Trikke when they asked how long the wheels lasted. I told them that I was about 3 months into the wheels that I have and the rear wheels seem to be about half worn down. She pointed out that they looked like they could use rotating. Aha! When I looked, I could plainly see that they were wearing unevenly and needed rotating. I had already been told that when you change wheels you need to spray the bolts first with a lubricant like WD-40 and then wait at least an hour. I sprayed them once and then the next night and even then, I needed to tap the hex wrench with a hammer to loosen the bolt. The silver spacers between the wheel and the fork have to be gently tapped back into place before inserting the bolts (actually one side is a long cylindrical shaft that goes through the wheel) and then tightening slowly and evenly on each side until both sides are snug. The two hex wrenches are to tighten both bolts at the same time.