Possible inconstancy is tfl data:

gistfile1.txt

I'm seeing the same train (same LCID) appearing at multiple platforms:  

url: 

http://cloud.tfl.gov.uk/TrackerNet/PredictionDetailed/C/LYS

So for example LCID 1107207 is showing in Westbound platform 1 and 2. 

The only difference I can see between the two records are the, SecondsTo, TimeTo and DepartInterval which are slightly different.


1:  <T LCID="1107207" SetNo="131" TripNo="4" SecondsTo="1265" TimeTo="21:00" Location="Between Theydon Bois and Debden" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:50" DepartInterval="1265" Departed="0" Direction="0" IsStalled="0" TrackCode="TC8016" LN="C" />

2:  <T LCID="1107207" SetNo="131" TripNo="4" SecondsTo="1222" TimeTo="20:00" Location="Between Theydon Bois and Debden" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:50" DepartInterval="1222" Departed="0" Direction="0" IsStalled="0" TrackCode="TC8016" LN="C" />

LYS

<?xml version="1.0" encoding="utf-8"?>
<ROOT xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://trackernet.lul.co.uk">
  <Disclaimer>This system is an INFORMATION ONLY system, relying entirely on 
				information received from the relevant Operational Railway Control System(s). It is NOT 
				considered a safety related system in the Railway Engineering sense. However, 
				the information reported may trigger user intervention by staff regarding possible 
				incidents on the railway, and confirmation of the situation observed should be obtained prior 
				to any corrective action being taken.</Disclaimer>
  <WhenCreated>4 Jan 2015 9:05:52</WhenCreated>
  <Line>C</Line>
  <LineName>Central Line</LineName>
  <S Code="LYS" Mess="" N="Leytonstone." CurTime="9:05:52">
    <P N="Westbound - Platform 1" Num="1" TrackCode="TC5748B" NextTrain="false">
      <T LCID="1107183" SetNo="102" TripNo="5" SecondsTo="273" TimeTo="5:00" Location="Approaching Redbridge" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:49" DepartInterval="273" Departed="0" Direction="0" IsStalled="0" TrackCode="TC6104" LN="C" />
      <T LCID="1106724" SetNo="130" TripNo="4" SecondsTo="641" TimeTo="11:00" Location="Between Buckhurst Hill and Woodford" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:31" DepartInterval="641" Departed="0" Direction="0" IsStalled="0" TrackCode="TC7514" LN="C" />
      <T LCID="1107411" SetNo="113" TripNo="3" SecondsTo="848" TimeTo="14:00" Location="At Hainault" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:04:05" DepartInterval="848" Departed="0" Direction="0" IsStalled="0" TrackCode="TC6711" LN="C" />
      <T LCID="1107207" SetNo="131" TripNo="4" SecondsTo="1265" TimeTo="21:00" Location="Between Theydon Bois and Debden" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:50" DepartInterval="1265" Departed="0" Direction="0" IsStalled="0" TrackCode="TC8016" LN="C" />
      <T LCID="1107280" SetNo="132" TripNo="4" SecondsTo="1525" TimeTo="25:00" Location="At Epping" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:04:20" DepartInterval="1525" Departed="0" Direction="0" IsStalled="0" TrackCode="TC8221" LN="C" />
    </P>
    <P N="Westbound - Platform 2" Num="2" TrackCode="TC5718" NextTrain="false">
      <T LCID="1106725" SetNo="127" TripNo="4" SecondsTo="0" TimeTo="-" Location="At Platform" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:04:09" DepartInterval="0" Departed="0" Direction="0" IsStalled="0" TrackCode="TC5718" LN="C" />
      <T LCID="1107183" SetNo="102" TripNo="5" SecondsTo="364" TimeTo="6:00" Location="Approaching Redbridge" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:49" DepartInterval="364" Departed="0" Direction="0" IsStalled="0" TrackCode="TC6104" LN="C" />
      <T LCID="1106724" SetNo="130" TripNo="4" SecondsTo="598" TimeTo="10:00" Location="Between Buckhurst Hill and Woodford" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:31" DepartInterval="598" Departed="0" Direction="0" IsStalled="0" TrackCode="TC7514" LN="C" />
      <T LCID="1107411" SetNo="113" TripNo="3" SecondsTo="939" TimeTo="16:00" Location="At Hainault" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:04:05" DepartInterval="939" Departed="0" Direction="0" IsStalled="0" TrackCode="TC6711" LN="C" />
      <T LCID="1107207" SetNo="131" TripNo="4" SecondsTo="1222" TimeTo="20:00" Location="Between Theydon Bois and Debden" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:05:50" DepartInterval="1222" Departed="0" Direction="0" IsStalled="0" TrackCode="TC8016" LN="C" />
      <T LCID="1107280" SetNo="132" TripNo="4" SecondsTo="1482" TimeTo="25:00" Location="At Epping" Destination="Holborn" DestCode="566" Order="0" DepartTime="9:04:20" DepartInterval="1482" Departed="0" Direction="0" IsStalled="0" TrackCode="TC8221" LN="C" />
    </P>
    <P N="Eastbound - Platform 3" Num="3" TrackCode="TC5711" NextTrain="false">
      <T LCID="1100731" SetNo="122" TripNo="4" SecondsTo="74" TimeTo="1:30" Location="Between Leyton and Leytonstone" Destination="Epping" DestCode="530" Order="0" DepartTime="9:05:47" DepartInterval="74" Departed="0" Direction="0" IsStalled="0" TrackCode="TC5623" LN="C" />
      <T LCID="1100720" SetNo="115" TripNo="4" SecondsTo="447" TimeTo="7:00" Location="Between Mile End and Stratford" Destination="Hainault via Newbury Park" DestCode="532" Order="0" DepartTime="9:05:50" DepartInterval="447" Departed="0" Direction="0" IsStalled="0" TrackCode="TC5443" LN="C" />
      <T LCID="1106726" SetNo="123" TripNo="3" SecondsTo="781" TimeTo="13:00" Location="Between Liverpool Street and Bethnal Green" Destination="Epping" DestCode="530" Order="0" DepartTime="9:05:45" DepartInterval="781" Departed="0" Direction="0" IsStalled="0" TrackCode="TC5213" LN="C" />
      <T LCID="1107442" SetNo="106" TripNo="5" SecondsTo="1155" TimeTo="19:00" Location="Approaching Bank" Destination="Woodford Via Hainault" DestCode="531" Order="0" DepartTime="9:05:48" DepartInterval="1155" Departed="0" Direction="0" IsStalled="0" TrackCode="TC4705" LN="C" />
    </P>
  </S>
</ROOT>

My understanding is that this happens when a line passes through two consecutive platform numbers at the same station. Presumably larger / longer platforms and presumably above ground locations.