The lvl50 ring race... :)

I thought there was a screenshot of someone wearing both...?

That person had on the lvl 50 or lvl 30 Lilin's Ring (that add +2 and +1 respectively). They didn't exist in KMS and were original to GMS. When GMS imported the data for the Adventurer Rings there was a block for the lvl 70 Lilin's Ring (the one that exists in KMS) but there was no block for the lvl 50 and 30 versions, so you can wear either of them with the Adventurer rings. It will get fixed eventually, so don't feel so bad if you don't have those rings.