Not a bug, just extremely unlikely as the code is trying real hard not to do that. But it's not a 100% guarantee it never will. This could be resolved by rewriting the mechanism for selecting new issues, but the odds are so small it's not worth the effort, IMHO.
Ballotonia
"Een volk dat voor tirannen zwicht zal meer dan lijf en goed verliezen, dan dooft het licht…" -- H.M. van Randwijk