because back when there was the thing with the banks or whatever the group that caused this, there were a lot of VNs that were blocked because of erotic content if i'm not wrong. So creator had to create a second "VN" to keep the updates. So one is this the SFW version if i'm not wrong, and the other one the original.
But yeah all of this is just from memory, go check yourself, i think there was an update post back then about it. So better check in case i said anything wrong.