The 'Lighter' Side Of The Force
most military personnel have a "go bag" Let get the hell out and go. Landon did too
1. Landon was not in the military in ESB. He was a businessman and Admninistrator of Cloud City.2. Landon's name is Lando;)
The most canonical answer you will get is from billy dee williams who quoted george lucas on set explaining to him that lando and han share a military history and this outfit was the uniform. They are landos clothes not hans and are different sizes and were made for billy.
Even in the Lando Calrissian books that tell of his adventures when he owned the Falcon, there is no mention of Lando having a military background. It's possible he still had some stuff stored on the Falcon when Han won it from him in that sabacc game, but there is also another possibility. Perhaps when they got to the rebel fleet, Leia sent him to someone in supply department so he could get some fresh clothes after their escape from Cloud City.
What about the battle they discussed in ROTJ? come on, man.
Eh, I'd rather like to think that Lando cra--- uh 'soiled' his clothes in the getaway and then just used what clothes han had left behind... I think that makes the most sense...