When I only have one precious prototype of my idea, I find myself very protective of it. I avoid doing anything risky that might break it. I have learned that building extra samples is usually a good idea. I like to say if I need one I build two... if I need two, I buy three or four. Rarely a time when I regret buying the extra part.
Something's going to break, or you're going to strip out the threads, or you're going to paint one of them wrong, or you're going to want an extra one unexpectedly for a marketing photo. It's hard to go back in time and order spare parts to keep your schedule moving forward. So a little extra materials cost every time you buy parts or a little extra printing time to add a few spares onto your build sheet is time and material well spent. A pair and a spare.