function areAllInstancesEqualWithinHost(projectOrAddon, addonName) {
  const { realAddon, proxies } = getAllAddonsByNameWithinHost(projectOrAddon, addonName);
  return proxies.length > 0 && proxies.every((proxy) => proxy[TARGET_INSTANCE] === realAddon);
}
Returns whether all instances within a given host are equal (i.e., that there's a single
"real addon") and all proxies have the `TARGET_INSTANCE` property that's strictly equal to
the aforementioned real addon

@name areAllInstancesEqualWithinHost
@param {Project|Addon} projectOrAddon
@param {string} addonName
@returns {boolean}