Guaranteed once and only once notifications using database(O

We have seen cases when a standard oracle adapter fails to
send notification events for a database insert operation.
This occurs rarely and have any of you experienced this
problem?

Along with ATCs, the Notifier adapter was introduced. As per
ATC docs, one of the advantages for this adapter is that
this provides guaranteed once and only once notifications.

This means the standard oracle adapters did not guarantee
once and only once notifications for a database insert
operation?

What about the intelligent oracle adapters? Whether this
gurantees once and only once notifications?

Any comments/suggestions are appreciated