Fix hovercard behavior for multiple copies of the same object

Summary: Ref T8980. Previously, if you had like T123 T123 T123 and waved your mouse over them, we wouldn't move the card. Now, move the card.

Test Plan: Waved mouse. Saw the card move.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8980

Differential Revision: https://secure.phabricator.com/D14881