Yeah, it was when I called Taylor this morning that even they were intially stumped...
The SN is actually in their records twice. The first time, it lists the guitar as a 2012 GS5-12 with a spruce top, sold to Melodee Music. The only things funky about that are the missing "e" and the spruce top (when the guitar was actually at the road show @ Melodee, it already had electronics and clearly had a cedar top).
The second time it shows in their records, it is annotated as a 2012 GS5e-12 with the ES2 and a cedar top. There is a note about adding the ES2, but not why. The original spruce top appears to be more a misprint than anything else, although they can't verify. They have a hunch that it's more an initial misprint than re-topped.
The only thing they can gather is that the guitar was kicked around Taylor from road show to road show, demo to demo and maybe had various artists or potential customers playing it, then they put the ES2 on the guitar to let people test drive it and see what they thought. There were no notes exactly why ES2 was even added, but being a 2012 guitar that was the closest thing they could guess.
Nick