''Right, and that's exactly "DualLicensed" means. a) You get it under [GPL]: you may redistribute it and must do so under [GPL]. b) You buy it: you may not redistribute it. c) You get it from a third party: because of a)/b), this is only possible if the third party obtained it under [GPL], so you get it under [GPL], even if you'd have to buy it if you were to get it from the author. This is why I wrote "the legal implications may be confusing". Exactly the same applies to [MySQL] -- you can acquire [MySQL] from a third party under [GPL], even for commercial use, except MySQL AB won't support you then.'' --AristotlePagaltzis 

  

 ''Not true, according to http://dansguardian.org/?page=copyright2 - you download it, and then it's GPL. The page seems to be heavy handed wording to try and make you think you can't do certain things, but once you've obtained it, I see no reason you can't take it and do whatever you want with it, as you are allowed to redistribute it under the terms of the GPL.'' -- CraigBox 

  

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 A pioneer of the general sense of dual licensing was [Perl], which is distributed under the terms of the ArtisticLicense as well as the [GPL]. However, since it is [Free] under ''both'' licenses, it is not the canonical example and not what people generally refer to as DualLicensed. The difference is that [GPL] is a CopyLeft license, while the ArtisticLicense is not. [Perl]'s situation is unique because no circumstances force you to explicitly commit to either license, so you can redistribute the package under ''both'' licenses yourself.