In the seed 931718537, you can notice both iron ore and coal ore on the same title.
Screenshot:
Map generator settings: Default
I think it's a bug because ores are supposed to act like titles, so two kinds of ores should not overlap.
[0.15.31] Ores overlapping
Re: [0.15.31] Ores overlapping
Wow... someone really has to tell me how to use search engines. I get no results...