it is so much easier (and 'legal') to have second account with another Star-carrier than to have an ('unlegal') second Mileage Plus account.

The benefits are also better that way: you may then choose, segment by segment, which program fits better (depending on minimum miles rules, current promotions, upgrades on any fare/selected fares, etc. etc.).

That's one of the reasons why I have status with Mileage Plus and miles&more.