Not sure if this has already been posted about, but as the title suggests sometimes it says I have a "Duplicate Session" open on another device and exits out of Subterfuge. Not hugely annoying, just relaunching gets me back in, but it's still a bit of a nuisance. It only happens when I unlock my phone straight into Subterfuge - if I hit the Home button before locking, and then re-launch Subterfuge, it hasn't happened yet.

I'm running Android 5.0.1 on an LG G3

This is not a bug but a security feature.

I guess I should've specified that I am not, indeed, using it on another device. The only thing I can think of is my being logged into the forums while playing the game. But otherwise I only have the one device (my LG G3), not using it on any other device but it still says I am.

Is this intended functionality? If so maybe change the pop-up to say "inactivity" instead of "multiple sessions" when that isn't actually the case.

This is actually happening for me as well. Like you said, only playing it on one device, but still get the popup.

Thanks for pointing it out. The devs monitor the forum and will surely add it to their to-do list, after some of the urgent bugs.