Redundant certificate in keyring

[Robert J. Hansen]

I don't know how this came to pass, but:

PS C:\Users\Robert J. Hansen\Documents> gpg --list-keys 12d9199d7b3b7495
pub   dsa2048/12D9199D7B3B7495 2017-07-26 [SCA]
      1BE9AAB825A55E48195F1A0312D9199D7B3B7495
uid                 [ unknown] Tobias Schultz <tobias.schultz at cadooz.de>
sub   elg2048/B57E2F27C75F8668 2017-07-26 [E]

pub   dsa2048/12D9199D7B3B7495 2017-07-26 [SCA]
      1BE9AAB825A55E48195F1A0312D9199D7B3B7495
uid                 [ unknown] Tobias Schultz <tobias.schultz at cadooz.de>
sub   elg2048/B57E2F27C75F8668 2017-07-26 [E]

(Windows 10, GnuPG 2.2.0.)

Somehow, this cert got introduced into my keyring twice.  I don't know
how and I don't really know when; I only found out about it after a
script I run every month broke horribly, since it expects a given cert
to only appear once in the keyring.

I don't ever edit my keybox file directly.

Deleting that cert deleted only one of the two certs, too.

There appears to be a bug in the keybox code; unfortunately, I'm not
able to give much in the way of details.  :(