TCP: a practical question

Greetings.

Normally TCP connection establishment is a three packet sequence.

C -> S (Syn)
S -> C (Syn|Ack)
C -> S (Ack)

TCP specification (rfc 793) mentions about a simultaneous open and
it's use in distributed set ups.
In this case the handshake would proceed as follows:

C -> S (Syn) .. 1
S -> C (Syn) .. 2
(1 and 2 happends almost simultaneously)
C -> S (Syn|Ack)
S -> C (Syn|Ack)

My question is do we see this behavior in the practical world ?

Thanks
Ashley

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