Yes they are different legs.  One is finishing leg 3, the other is finishing leg 5. 

interesting this could mean a faster boat in a pursuit race loses all its rights as it overtakes the fleet.
Seems unfair.
I can see the rule applying when you are on different legs windward or leeward.

Are then both not on the same leg a windward leg?

RRS 23.2 After the starting signal this rule does not apply when the boat is sailing he proper course. So as the two boats are sailing after the starting signal then the rule is not relevant.

what if you wanted to luff on a run?

If your sailing as described in proper course then you don't loose any rights. The question that has to be answered in a hearing would be, why did you wanted to luff.

The faster boat in the pursuit race does not lose all of its rights, it just loses its rights when it sails off its proper course.  If we assume for a minute that we are on different legs that it is actually the slower boat (who started earlier in a pursuit race) that is at more of a disadvantage.  The slower boat might want to luff up the faster boat as the went past to slow them down.  They can't do this (well not past their proper course) until they are on the same leg.  The faster boat who wants to make up their time is less likely to want to run up the elapsed time getting tied up with the slower boat.  
I would suggest that one thought picture here is that in some imaginary world leg 3 and leg 5 are nowhere near each other so the boats would not be able to interfere with each other.  Since for practical purposes we run them in the same physical location, we limit the amount of interference.  

Craig, it IS relevant.
Typical quiz/situation: windward mark, boat L does not bear away, preventing boat W also from bearing away.
Usually the quiz/situation/solution ends as: L is not obliged to bear away at the mark, if RRS 17 is not in force (proper course)
Well, i would add: if RRS 17 AND RRS 23.2 are not in force, AND if the interference does not break RRS 2, meaning if that interference is made only for L score advantage, and not in favour of another boat, in a sort of team racing.
And 23.2 would apply if both boats  are on different legs, as per my question.

To the original question: The boats are both on the same leg of the course.  See Case 126.  The rule is based on the mark the leg ends at, e.g. "windward leg to the windward mark".

The rules do not require a boat to know what lap a boat is on.  That would only add an unsafe condition and ambiguity.  It only requires you to know they are headed to the same mark that you are.  

The clause "However, after the stating signal this rule does not apply when the boat is sailing her proper course" prevents hunting. Boats on different legs of the course are all sailing under the rules as normal and a boat on a run and going to weather do what they always do: all are sailing normally under 10, 11 and such.  
The clause prevents hunting but allows you to sail with rights that cause a give way boat to alter course to avoid you; as long as you are on your proper course.

Wayne, I got your point, but i'm still not convinced.
1) the case 126 is a different situation.
2) ."" sailing on the leg which is consistent "" is ok, as a general sentence, but the example was about a boat apparently wandering about. A course going to a mark can be consistent to that mark, and still not being on the same leg.
3) I agree that a boat is not obliged to know which leg is the other boat, ok, agreed, but as long as she is not hindering  other boats; otherwise, she better know.

Well that's my thought.

I admit,  I'm stubborn....

Merriam Webster:

Both can travel on the same branch, but be at different portions of their trips. This doesn't help us at all. Lets look at the rules.

If all legs to any windward mark are considered a upwind leg, how do we rule on 28.1 or 31.1? Are you allowed to touch the mark 2 on your first windward leg? Do you have to leave this mark always to port? Or is the starting upwind leg a different leg?
This would be very messy to rule. And possibly even harder for the sailors to get their heads around on the water.

While we now have no problems with the rules 28 and 31, boats have to be aware of 23.2.
This rule has some fine print to it.

Rule 23 does not interfere with any other rules of part 2 regarding safety, because it does not grant room nor right-of-way.
In itself it is very limited. It only applies if a boat react to the presence of the other boat (as in no longer sailing her proper course) and she is interfering with it.

The terms "windward leg to the windward mark", "leg of the course to the leeward mark" and "leg from the windward mark to the offset mark" are describing what particular leg of the course they were sailing. We don't know if the course had multiple rounds.

In the answer 3 boat L was sailing upwind towards the offset mark. While she maybe also sailing toward windward, she is on her leg from point A to point B. Sailing in the same directions is not sailing on the same leg.

I'll venture out on a limb and try a different explanation!! 

 

Two boats sailing on a beat to windward are sometimes on the same leg of the course and at other times on another leg of the course.

 

We need a definition of the term “leg” as it is used in rule 23.2. The definition of sailing the course doesn’t help, it talks about marks but not legs. However, the second sentence of rule 28.1 does seem to define the term leg. A leg is defined by the marks that “begin, bound or end the leg she is sailing.”

 

 

Therefore, the first leg (start to first mark) and last leg (last mark to finish) are not repeated, so only boats sailing from the start to the first mark, or the last mark to the finish are on those legs.

A boats on a leg that uses the same marks to begin, bound and end the leg are on the same leg. For boats on a beat to windward that would be leg 3, leg 5, leg 7, etc, which only occurs on a course with six or more legs.

Leg 1 : Start to Mark 1
Leg 2 : Mark 1 to Mark 2

Leg 3 : Mark 2 to Mark 1

Leg 4 : Mark 1 to Mark 2
Leg 5 : Mark 2 to Mark 1 
Leg 6 : Mark 1 to Finish

For boats on a run that would be leg 2, leg 4, leg 6, etc, which only occurs on a course with five or more legs.
 
Leg 1 : Start to Mark 1
Leg 2 : Mark 1 to Mark 2

Leg 3 : Mark 2 to Mark 1

Leg 4 : Mark 1 to Mark 2
Leg 5 : Mark 2 to Finish

Seems a good reason to not run anything longer than a double windward leeward.
 

Mark - the real reason not to run something more than a double W/L course is that you have to count really high to know when to go to the finish! :-D

Mark, I like your reductive approach.  That said, I do think 28.1 can be read in a way that is compatible with both “leg” interpretations (unique or repeatable). 

Since it’s undefined, we commonly refer to legs by their unique numbers, in the order that they are sailed. If we were ID’ing an incident for a protest filing, we would refer to the leg as “the 3rd leg of the course” interchangeably with  “2nd windward leg”, each unique. 

It is seldom "reasonably possible" to be positive that a boat is not on the "same leg," as discussed above.
Therefore 23.2's particulars exonerate any misunderstanding.
The overtaking boat should expect to be luffed.
No revision of 23.2 or definition of "leg" is needed.

well, in my area, winter championship, 110 boats, an event to make happy the club members rather than sport;  boats all together from 14 to 42 feets, some to make 3 rounds, some two rounds, and half the fleet at good level, the other half struggling with the spinnaker aound the keel, or trying to bring mark 1 home every time they round it, having boat at the mark at same time but different leg, it's NORMALITY