If a list of target endpoints for sending view updates contains
duplicates, it results in benign (but annoying) broken promise
errors happening due to duplicated write response handlers being
instantiated for a single endpoint.
In order to avoid such errors, target remote endpoints are deduplicated
from the list of pending endpoints.
A similar issue (#5459) solved the case for duplicated local endpoints,
but that didn't solve the general case.
Fixes#7572Closes#7641
c0d72b4491