I'm not 100% sure, but I think this is a choice of one of a few licenses for the software rather than a dual license. The licenses aren't coherent if you apply

I'm not 100% sure, but I think this is a choice of one of a few licenses for the software rather than a dual license. The licenses aren't coherent if you apply the licenses simultaneously, but I think only one of the licenses need apply to the software for a given user. So you can release free and open source software which might be used for military purposes, OR you can release closed sourced software, but it can't be used for military purposes. The effect is that if your software will be used for military purposes you have to release it as free and open source software. In this case it's not a dual license where you're bound by the terms of both licenses, it's a situation where you choose one of the licenses based on which set of terms you can comply with. Multi-option licenses like this are frequently used for proprietary software to enforce tiered pricing (such as nonprofit/personal/corporate licenses all applying to the same software but different licensees). This is my interpretation, but I'm not a lawyer. I wouldn't stake my business on my interpretation without consulting a lawyer and neither should you.