See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6140
We don't cover this corner case as it has low chance for reproduction.
Precisely, the requirements are following:
1. vmagent need to be configured with multiple identical `remoteWrite.url` flags;
2. At least one of the persistent queues need to be non-empty, which already
signalizes about issues with setup;
3. vmagent need to be restarted with removing of one of `remoteWrite.url` flags.
We do not document this case in vmagent.md as it seems to be a rare corner case
and its explanation will require too much of explanation and confuse users.
Signed-off-by: hagen1778 <roman@victoriametrics.com>