Documentation Paragraph 3.5 "Already Submitted" is not a validation

[radboudp]

"Already Submitted" is not a rejection reason. It describes that same ID and same content should be considered a retransmit of an already received message. This is an exemption of the "Duplicate Identifier" and should be added as a note to the description of that validation.

[tomwetjens]

Discussed proposal:

Change the description of the "Duplicate Identifier": remove ", and has already been used for a message with different content"

Remove "Already Submitted" completely.