As noted by mystikx21, selecting the religious belief Feed the World would appear to give +3 x2 = +6 in total.
GEM 1.13.4/[CivUP 2.5.2]
- Screenshot 1: note the Shrine tooltip does not reflect the effects of chosen religious beliefs; (I have chosen via IGE Feed the World and Ancestor Worship).
- Screenshot 2: food breakdown is highlighted and shows that terrain is giving 4 (which is correct), but that religion and buildings are each giving 3. The only 'food building' in the city, however, is the religiously enhanced Shrine, so Feed the World's effect is doubled for some reason.
- Screenshot 3: included to show that Ancient Worship works as it should, i.e. a total of 4 (1 from Great Mosque of Djenne, 3 from the Shrine with Ancient Worship).
Lua log attached and since this is just an IGE example I can easily replicate another if needed. - Screenshot 2: food breakdown is highlighted and shows that terrain is giving 4 (which is correct), but that religion and buildings are each giving 3. The only 'food building' in the city, however, is the religiously enhanced Shrine, so Feed the World's effect is doubled for some reason.
- Screenshot 3: included to show that Ancient Worship works as it should, i.e. a total of 4 (1 from Great Mosque of Djenne, 3 from the Shrine with Ancient Worship).
GEM 1.13.4/[CivUP 2.5.2]