I am not sure how this happened, but while putting on my new weapon on my BLM today, I noticed that I was wearing the lvl 45 AF BLM helm, as well as my Darklight Cowl of Casting. Somehow the gearset got saved with both equipped at the same time.

ISP:
Timewarner Cable

Type of Internet Connection:
Cable

Internet Connection Speed:
30mbps DL

Date & Time:
3:30am PST - noticed (not sure when it saved)

Frequency:
Unknown

Character Name:
Daenerys Stormborn

Race:
Miqo'te F

World:
Leviathan

Class/Level:
50 BLM

Steps:
Detailed steps on how the issue occurred.

Not entirely sure. The only thing I can think of is when I was rushing to put on my Darklight after hitting 50 (maybe 3 days ago?) I somehow managed to save the gearset with both the AF helm and Darklight Cowl both equipped. I think I just dropped the Darklight Cowl into my chest slot assuming it would unequip the AF helm. I'm leaving it as is for now (in case you want to check the Lodestone and see that my char actually has both equipped). I subtracted the stats from all equipped gear and got 272, then opened the bonus stats to get base int (242+30). This leads me to believe that stats from both items are being used.