Wow! Call me old-fashioned, but seems to me that if you have blue and white stripes as you home kit, you're only ever going to clash once in a blue moon with the oppo, and then only with their yellow kit or their red kit, in which case you'd wear the stripes. Might be missing something but can see no other possible reason for a randomly chosen third shirt other than to part tuats from their money.
Kerrrchiiing ££££ Spot on.