The comic book series "Planetary" by Warren Ellis plays directly on the DC multiverse being a retcon device. In the Planetary/Batman crossover, the story rotates between six versions of Batman. As detailed in this review, the first five are meant to be five previously published versions of Batman, but it's not clear whether the sixth (seen below) references anything or is purely a product of Ellis and artist John Cassaday. Could there have been published a one-off issue sometime with this Batman in it? There's more versions of batman than you can shake a stick at. :-)
The deluxe edition of the crossover issue includes Ellis original script, which might settle the issue, but I have not got hold of that.