Strange behaviour of Compare-Object cmdlet

PowerShell Help
1

Hello.

I have tried to compare two ArrayList objects which contain custom PsObjects (TCP connections) inside.

So, I have the $ArrList1 object, which has the next TCP connections:

PS D:\WindowsPowerShell\Scripts> $ArrList1 | where {$_.ProcessName -eq 'icq'}

LocalAddress   : 0.0.0.0
LocalPort      : 63857
RemoteAdderss  : 0.0.0.0
RemotePort     : 0
State          : Bound
AppliedSetting :
PID            : 12268
CreationTime   : 25.07.2019 22:43:57
ProcessName    : icq
ProcessPath    : C:\Users\tempuser\AppData\Roaming\ICQ\bin\icq.exe


LocalAddress   : 0.0.0.0
LocalPort      : 63856
RemoteAdderss  : 0.0.0.0
RemotePort     : 0
State          : Bound
AppliedSetting :
PID            : 12268
CreationTime   : 25.07.2019 22:43:55
ProcessName    : icq
ProcessPath    : C:\Users\tempuser\AppData\Roaming\ICQ\bin\icq.exe

LocalAddress   : 0.0.0.0
LocalPort      : 63855
RemoteAdderss  : 0.0.0.0
RemotePort     : 0
State          : Bound
AppliedSetting :
PID            : 12268
CreationTime   : 25.07.2019 22:43:49
ProcessName    : icq
ProcessPath    : C:\Users\tempuser\AppData\Roaming\ICQ\bin\icq.exe

LocalAddress   : 0.0.0.0
LocalPort      : 63854
RemoteAdderss  : 0.0.0.0
RemotePort     : 0
State          : Bound
AppliedSetting :
PID            : 12268
CreationTime   : 25.07.2019 22:43:49
ProcessName    : icq
ProcessPath    : C:\Users\tempuser\AppData\Roaming\ICQ\bin\icq.exe

LocalAddress   : 127.0.0.1
LocalPort      : 63845
RemoteAdderss  : 127.0.0.1
RemotePort     : 63846
State          : Established
AppliedSetting : Internet
PID            : 12268
CreationTime   : 25.07.2019 22:43:46
ProcessName    : icq
ProcessPath    : C:\Users\tempuser\AppData\Roaming\ICQ\bin\icq.exe

LocalAddress   : 192.168.1.2
LocalPort      : 63844
RemoteAdderss  : 178.237.20.123
RemotePort     : 443
State          : Established
AppliedSetting : Internet
PID            : 12268
CreationTime   : 25.07.2019 22:43:46
ProcessName    : icq
ProcessPath    : C:\Users\tempuser\AppData\Roaming\ICQ\bin\icq.exe
When I have tried to kill icq.exe (and to close all connections of this process) and to make the new ArrayList object after this - $ArrList2, I have got the next result:
PS D:\WindowsPowerShell\Scripts> $ArrList2 | where {$_.ProcessName -eq 'icq'} | ft -AutoSize no 'icq.exe' process connections. When I have tried to compare these objects: Compare-Object -ReferenceObject $ArrList1 -DifferenceObject $ArrList2 -PassThru - I couldn't found any 'icq' processes in result with SideIndicator '<='.
Why have I this behavior ? I think that all 'icq' processes (which connections was closed) should be in 'ReferenceObject' and should be shown with '<=' SideIndicator. Am I right ?
2

Decided.

I have added to PID process property to Compare-Object:

Compare-Object -ReferenceObject $ArrList1 -DifferenceObject $ArrList2 -Property PID -PassThru

After this Compare-Object compares PsObject objects correctly.