Oyster PAYG double-back OSI query

[Leisurefirst]

Hi there,
Had a strange PAYG experience this morning.
Not out of pocket (taken care of by the cap) but I am intrigued...
Travelling to Meridian Water by the H&C/Circle then either to via King's Cross (Victoria Line) to Tottenham Hale thence onto Meridan Water either by train (if connection good) or by 192 bus or via Liverpool Street.
Happened to check before leaving if trains were running from Liverpool Street to Tottenham Hale as travelling with somebody who needs no stairs if possible and minimum walking.
(We sometimes do Liverpool Street if not in a hurry as only a handful of steps or the lift to change. If we go via King's Cross rather exit the H&C/Circle and take the long flight of steps up to the Victoria Line escalators we take the lift up then exit and walk along the subway towards the Euston Road exit then down again to the Victoria Line via the other lift there and the escalators).
Saw the football was on at the Emirates at 12.30 and wanted to avoid the Vic Line so settled on via Liverpool Street.
Happened to check trains to Meridan Water and surprised to see a direct train from Liverpool Street but only one per hour and we were just going to miss it by five minutes or less.
When our H&C/Circle arrived at King's Cross I made a last minute decision to bale out and go via the Vic Line to Tottenham Hale to try and meet up with the train to Meridan Water.
When we got to the lift by the Euston Road exit end of the subway I noticed on the departure boards that the Vic Line was running at 7/8 minute intervals.
With regret (and huge apologies because of the walk back to the H&C platform) went back and carried on to Liverpool Street, took the train to Tottenham Hale, then the 192 bus in order to avoid what would have been very packed Victoria Line services.
Sorry for all that long back story but my question is this...
I exited the H&C at King's Cross with the intention of touching back in and taking the Victoria Line.
I didn't, but touched back in at the H&C and then out again at Liverpool Street LU and back in at Liverpool Street NR and out at Tottenham Hale.
I could tell by by balance at Tottenham Hale that I probably got charged two fares and I can understand that.
(It in fact balanced out anyway as with the bus journeys there and back and the return tube journey I met the NR Railcard cap).
My question us when we returned to our home tube I checked the journey history and rather than being charged one £1.65 fare to King's Cross then another £1.85 from King's Cross to Tottenham Hale I had in fact been charged £1.65 to Liverpool Street (my doubling back not resulting in two fares) but then another £1.85 from Liverpool Street to Tottenham Hale.
Why did the system treat my exit and re-entry at King's Cross as one OSI? journey but then the NR part at Liverpool Street not as an OSI but separately?

Edit... I assume it was because Oyster would expect somebody to travel directly from King's Cross to Tottenham Hale on the Vic and not via Liverpool Street that it charged two fares?

 

[island]

I've read through a few times but because of all the extraneous detail I am struggling to work out what exactly you did. It may be, for example, that you exceeded the OSI time limit on one occasion but not the other, or that you exceeded a maximum journey time whilst out of the station and therefore had to start a new journey with your next touch in.

Can you please list the touches in and out you made, ideally with the times? Or post an extract from your journey history?

 

[PeterC]

A timeout while on the concourse Liverpool Street was my first thought. The other thought was that you simply misread your journey history. A second minimum fare would be logged at Liverpool Street but adjusted on touch out.

 

[MikeWh]

Agreed that we need to see your journey history to diagnose exactly what happened. In the meantime, do you know which gatelines you used at Kings Cross? There is an internal OSI so if you exit by one and enter by another it will join the journey up.

 

[Leisurefirst]

Thanks, I exited through the H&C gateline then re-entered within 5 minutes.
That seems to have split the journeys.

 

[MikeWh]

Yes, Oyster journey history can be confusing when expanded out. But your two journeys were split at Kings Cross, not Liverpool Street. If you'd gone round the corridors and used a different gate to get back in then it would have been one journey.

 

[Leisurefirst]

Yes, Oyster journey history can be confusing when expanded out. But your two journeys were split at Kings Cross, not Liverpool Street. If you'd gone round the corridors and used a different gate to get back in then it would have been one journey.

Thanks.
I hadn't thought of doing that!

 

[swt_passenger]

With hindsight, why did you go through a gateline at Kings Cross? Isn’t there interchange on the paid side of the barriers between all the lines?

 

[Leisurefirst]

With hindsight, why did you go through a gateline at Kings Cross? Isn’t there interchange on the paid side of the barriers between all the lines?

No worries, was the reason for my regrettably lengthy essay in my OP!
Was because I was travelling with someone who needs preferably to avoid stairs so we always use the lift up and exit through the H&C ticket hall, walk along the subway and re-enter the "tube" lines via their ticket hall and use the lift(s) or escalators which is an OSI.
It was at the end of the subway I noticed the 7-8 minute Victoria Line intervals on the departures board there and with the football on at the Emirates decided to walk back down the subway and carry on to Liverpool Street and NR instead to avoid the crowds as they need a seat.
As MikeWh suggested I should have let them go back (they have a Freedom Pass) and used the "tube" gateline and gone back down the stairs to the sub-surface lines to mett them.
No harm done as the subsequent bus journeys meant I reached the PAYG cap anyway, I was just intrigued as to why the journey was still one despite the exit & re-entry as far as Liverpool Street yet the final leg to Tottenham Hale made it two.

 

[swt_passenger]

No worries, was the reason for my regrettably lengthy essay in my OP!
Because I was travelling with someone who needs preferably to avoid stairs so we always use the lift up and exit through the H&C, walk along the subway and re-enter the "tube" lines via their ticket hall and use the lift(s) or escalators.
It was at the end of the subway I noticed the 7-8 minute Victoria Line intervals and with the football on at the Emirates decided to walk back down the subway and carry on to Liverpool Street and NR instead to avoid the crowds as they need a seat.
As MikeWh suggested I should have let them go back (they have a Freedom Pass) and used the "tube" gateline and gone back down the stairs to the sub-surface lines.
No harm done as the subsequent bus journeys meant I reached the PAYG cap anyway, I was just intrigued as to why the journey was still one despite the exit & re-entry as far as Liverpool Street yet the final leg to Tottenham Hale made it two.

Ah, thanks for taking the time to explain.