My Question is that that we are to webmasters and having differnet sites he have its adsense account and me have mine i have 2 domains of same site one is .com the one is .net .com is hosted at my sever and .net is hosted at his sever when some time my forum of .com gets down I make .net active at there place what we have done that same forum with different domain .net is back up domain u can say that so he put the adsenes code of his account to the back up forum which is .com so will it be a problem or not ?
i think its not going to be a problem for adsense as long you put 1 pub-id in one page. the problem will come from your indexed page in the SE