In Asia they're often like that. When I was teaching in Thailand I had some students I'd play footy with. One of them was wearing a United top and City bottoms. That sort of thing is pretty common.
Seems crazy to me. Looks like it's more like a trend over there, weird. Where I live, it's a lot about LFC and United and it's true that LFC fans can end up supporting Everton if they are better placed to beat United, saying it's the same town, but it's more because of United hate and the first team is still LFC if there is a direct choice between LFC and Everton. United fans were very happy to see City beating us to the league last season.