2 redundant deepslate generate on the right side of the minecraft:ancient_city/city_center_2 and minecraft:ancient_city/city_center_3

I can confirm this behavior though this doesn't really appear to affect gameplay in any shape. This may be intended or a "Won't Fix", however, that isn't my call to make. You can run the following commands to reproduce this.

/setblock ~ ~ ~ minecraft:structure_block{mode:"LOAD",name:"ancient_city/city_center/city_center_1"}

/setblock ~ ~ ~ minecraft:structure_block{mode:"LOAD",name:"ancient_city/city_center/city_center_2"}

/setblock ~ ~ ~ minecraft:structure_block{mode:"LOAD",name:"ancient_city/city_center/city_center_3"}