SCTP handles association setup collision such that only a single association is established in case both peers try establishing an association to the other peer, provided that both peers try connecting to an SCTP port which was opened by the peer SCTP instance.
The association setup sequence looks as follows:
SCTP association setup collision sequence
The corresponding Wireshark trace looks as follows:
SCTP association setup collision Wireshark trace
The trace is available for download from https://wiki.wireshark.org/SampleCaptures.