Mike Bresina raised the question to me in response to my posting of Rule
4.7.b as to when players may return to the ice.
 
  Well, I've read 4.3.b several times and suggest it needs rewording, though
I think I understand what it says, but herewith:
 
4.3.b  When conincidental major penalites (penalities assessed during the
same stoppage of paly) or coincidental penalities of equal duration,
including a major penalty, are assessed against players of both teams, all
penalized players shall take their places on the penalty bench and such
penalized shall not leave the penalty bench until the first stoppage of
play after the expiration of their respecitve penalties.
  Immediate substitutions on ice shall be made for an equal number of major
penalties penalities or coincidental penalties of equal duration, including
a major penalty, to each team so penalized and penalties of the players
for which substitutions have been made shall not be taken into account for
the purpose of the delayed penalty (see 4-8.a).
  [Paragraph deleted]
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  Sorry about typos on penalties and play (maybe others) - I'm doing this
on line because of the urgency of the situation (this is an excuse, not
an explanation.) (;-)
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  The key word on my quick reading is "equal".
 
Rule 5-6.b
Note 2:  Misconduct penalties, coincidental minor penalties, coincidental
major penalties and coincidental disqualification penalties shall not be
recorded on the timing device.  Players serving these penalties will be
alerted and released at the first stoppage of play after the expiration of the penalties.
  The referee shall describe to the captain the violation that caused the
misconduct penalty.
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  Mike's question pertained to immediate return to the ice for major
penalties - thinking that this was disallowed.  Rule 4-4a includes "A
player whose misconduct penalty has expired shall remain in the penalty
box until the next stoppage of play."  I don't find a corresponding
statement for major penalties.
 
AND Rule-3.a, second paragraph repeats 4-7.b verbatim except for the
lead-in phrase.  If my ambition holds out I'll write the rules editor
and ask that one or the other (preferably 4-3.a second paragraph [I
mis-cited it at the beginning of this paragraph] be stricken.  I dislike
the coverage being duplicated - it is especially troublesome during
revisions.