Eye of Singularity not destroying permanents

I have [[Eye of Singularity]] on the board and in response to my opponent playing a creature spell, I play [[Theoretical Duplication]] to create a token copy of the creature once it enters. Once the creature enters, I resolve the Eye's trigger first, then the Duplication, causing another Eye trigger. Things are working so far. However, once the token copy of the creature comes into play, the original creature my opponent controls is not destroyed.

According to the rulings for Eye:
If a permanent enters as a copy of another permanent, the permanent it is copying is destroyed and the copy stays on the battlefield. (2004-10-04)

Permanents with the same name as one already in play are also not being destroyed if played normally so it's probably not specific to a copy coming into play.

Start by locating the implementations and tests for Eye of Singularity and Theoretical Duplication, then reproduce the reported sequence in a game test or manual scenario. Check the handling of Eye triggers when a same-named permanent enters, including a copy, and consider the issue done when the original permanent is destroyed as described by the cited ruling.

Written by the indexing model from the issue text.