I am using the javascript library Datejs in my project, the library states in their website that the code is released under the MIT Licence but the code published on their GitHub account is published under Apache License, Version 2.0.

Is this a mistake ?! or it is OK to publish the same project under two licenses?

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    Note that in this specific case, the website simply seems to be horribly out of date. The “latest release” is from 2007, it links to Google Code rather than GitHub, and the copyright statement on the license page only covers the years 2006–2010. The MIT license seems to apply to those old releases, but not for the current state of the project, e.g. when downloading from Github. See also issue #72.
    – amon
    Commented Aug 22, 2018 at 12:07
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    I think this is sufficiently covered by the existing answer (use the license from the place where you downloaded it). My above comment is just providing DateJS-specific background.
    – amon
    Commented Aug 22, 2018 at 15:52
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    I've just raised an issue on GitHub to see what they have to say. Sometimes these things are accidental - e.g. the licence changes and someone forgets to get rid of a link to the old one.
    – Pharap
    Commented Aug 23, 2018 at 11:50
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    @HyyanAboFakher "hanks for the clarification, if I used the older releases, does the MIT license apply here? or because we are in 2018 then the apache license applies" If you use an old release, MIT applies. If you use a new release, Apache 2.0 applies. The new licence doesn't apply to the old code and the old licence doesn't apply to the new code. (Though really that ought to be a full question in itself, not a comment.)
    – Pharap
    Commented Aug 23, 2018 at 11:53
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    @Pharap thanks for your comment, things are clear for me now, BTW I have also opened an issue on Github but I closed it because of #72 Commented Aug 23, 2018 at 11:58

1 Answer 1


Generally it's best if a dual-licensed project is explicitly described as such in all the places where it is distributed, but there's no legal requirement for that to happen. Legally, the license which you acquired it is the license that you have to abide by. So if you download it from their website then use it under the MIT license, if you download it from GitHub, use it under the Apache license.

I guess the one case where it would matter is if you want to redistribute it yourself under both licenses. Unless one of the sites explicitly offers the project under both licenses I don't think it would be legal for you to redistribute it under both.


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