MAJIC9 ,
I heard this rumour , but a friend of mine , a green card holder does not live in the country but goes in the U.S every year for 3 weeks to maintain his residence ( he holds two passport as well , and I believe it helps ).
Myself I do not have a green card yet but I am working for an American company and they might sponsor me , who knows...???
Wish you all safe landings
GUSTO