It's a fashion statement to have each shoe tied differently? I know some young people wear different unmatched socks all the time.
Someone was in the process of changing the laces over, were interrupted and never got around to completing the task.
Someone bought 2 pairs of identical shoes, so they had 2 pairs and one of the pairs had laces one way and the other pair had the other way. The pairs then got mixed up with one shoe of each in a pair. That would mean there would be another pair of the same shoes, possibly with one shoe tied one way and one shoe tied the other way, somewhere else.
(The above might sound implausible, but often athletic shoe stores have a buy one pair.......get another pair for half price sales. I have bought 2 pairs of shoes at one time to save money.