When the message gap is detected the "Resend Request" FIX Message is sent and Session state is changed to "AwaitReplyOnResendRequest". By default, in this state, the incoming new messages (without the PossDupFlag (tag #43) flag) are ignored because we expect them to be re-sent later again with the PossDupFlag flag. This property allows to change this behavior and report the new messages anyway. Note: In this mode messages could be reported out of the original order: e.g. MsgSeqNum could be: 3 (original), 4 (original), 2 (PossDupFlag='Y'), 3 (PossDupFlag='Y'), 4 (PossDupFlag='Y') and some messages could be received two times: first time without PossDupFlag='Y' and second time - with this flag.

public virtual bool ReportNewMessagesWhileWaitingForMissedMessages { get; set; }