18w50a Elder Guardian Spawns - Multiplayer Server

on 18w50a snapshot server. Server runs windows server version 2016

What I expected to happen was...:
Only 3 Elder Guardians spawning in a single monument

What actually happened was...:
Single monument spawned 11 Elder Guardians

Steps to Reproduce:
1. Seed -8665477440668589383
2. Location X=-3408     Z=897
3.