Kerbal Space Program

If multiple KSPAddons have the same start scene parameter and have set the "once" parameter to true, only the first addon seen will load, and the others will silently fail. This causes mods which use once=true to conflict.

The issue is caused by the way AddonLoader tracks already-once-loaded addons. It adds a KSPAddon to a list, and it checks that list whenever it's loading a new KSPAddon, but KSPAddon does not override Equals, so it defaults to Attribute.Equals which performs a value type comparison. This means that any addon with the same start scene and "once" parameter will be considered equal, and the loader will skip it.

To reproduce: Create two classes tagged with KSPAddons with the same start scene and once=true. Only one addon will load, while the other silently fails.

To fix: Change AddonLoader's internal List<KSPAddon> to List<Type> and store the type of each addon class as it's run.

I've also written about this issue here: http://forum.kerbalspaceprogram.com/showthread.php/45107-KSPAddon-bug-causes-mod-incompatibilities