The 2014 Competitors Blue Book as currently posted on the MSA site does not appear to show any changes to flagging. Cannot find any mention of double waved yellows.
15.1.1.
At an incident where the track is obstructed, or
marshals are working at the trackside, the following
signals will be used:
(a) A STATIONARY Yellow at the post before a
WAVED Yellow.
(b) A waved Yellow flag at the post immediately
preceding the incident. NB: In very serious cases,
this flag may be supplemented by an additional
waved yellow flag at a preceding post. (The waved
yellow flag may also be supplemented by flashing
yellow warning lights).
(c) A stationary Green flag at the post immediately
after the incident.
(d) If the incident is well off the track and marshals
are not working at the trackside, the incident may
be indicated by a stationary yellow flag, followed
by a stationary green flag, or by a Hazard Area
board.