I did some digging and the two words have different etymologies. So it’s a coincidence. English has many words that share the same spelling but have different meanings/etymologies as well. “Fan” for example. For “tour”, the “tower” usage comes from the Latin “turrem” which also means “tower”, and the “tour” usage comes from the Latin “tournāre” which means “to turn”.
I did some digging and the two words have different etymologies. So it’s a coincidence. English has many words that share the same spelling but have different meanings/etymologies as well. “Fan” for example. For “tour”, the “tower” usage comes from the Latin “turrem” which also means “tower”, and the “tour” usage comes from the Latin “tournāre” which means “to turn”.
That’s super interesting, so it sounds like it’s just a shortened version of two different words. Words go on such long journeys.