There appears to be an issue for Jamzu players who do an update install with the new version (a new install or delete and reinstall should work fine). If Jamzu is updated, and the user selects the 2 player same device option, Jamzu will crash. This can be avoided, or fixed, with a clean install, or delete and reinstall, as mentioned.
I am currently compiling a fix for this, and it should be submitted to Apple tonight. Thanks for your patience!