i just updated to todays gdm 2.14.4-0ubuntu2 using the update-manager, and did not see this.
what did you use to do the upgrade?
do you have any other *dm package? kdm or xdm
** Changed in: gdm (Ubuntu)
Status: Unconfirmed => Needs Info
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Debconf asks to choose from one option
https://launchpad.net/bugs/42187