You are right Didimo, it is possible to submit a flight twice BUT even if the flight appears in the list, it is still subject to a manual validation so such cases rarely escape unnoticed.
More particularly, there is a check that no matter the submission date and time, the flight times for the same pilot do not overlap. If they do, there is a red flag raised on the server.
In most of the cases it is obviously about unintentional duplicates, which are deleted without additional comments. In the rare cases when we found the same flight submitted 10 times, be sure we asked the author for an explanation.
As of the other problem, there is the possibility to save the PIREP before submitting it. In this case, it can be submitted at a later time so there is no risk of losing it.
And, of course, these known issues are subject to improvements in the new Flight Logger version that is still under development.
Andrei