The list of layers in the layer index has one openembedded-core in it, as it should be. However, when you search for a recipe, you get two openembedded-core entries. For example http://layers.openembedded.org/layerindex/branch/krogoth/recipes/?q=pigz or http://layers.openembedded.org/layerindex/branch/krogoth/recipes/?q=busybox As far as I can see, this happens for all branches, but not for machines: http://layers.openembedded.org/layerindex/branch/master/machines/?q=qemuarm
This is an unfortunate side-effect of Elliot's fix for bug 9159: http://git.yoctoproject.org/cgit/cgit.cgi/layerindex-web/commit/?id=3155206e54413f72df3b3b41280eafd332a58ba4
The fix turned out to be relatively straightforward. I also tweaked the query slightly so that exact matches on recipe name show up first.
This is now fixed in master and the live instance at layers.openembedded.org.
Verified, it works ok