Honeywell VISTA 21iP: Zone Doubling, 6.2K Resistor Installation (Continued)

Conclusion of wiring 6.2K resistor for higher number doubled zone.

In order to use Zone Doubling, the panel is looking for a specific resistor value. In this case, the resistors are being put at the panel because there were no resistors at the end of line, and in order to do Zone Doubling you MUST use resistors. Zone Doubling can only be used on Normally Closed sensors. If you have sensors with resistors in parallel at the end of line, that would mean these must be Normally Open sensors, so they are not compatible with Zone Doubling. If you wanted to use NC sensors with zone doubling, you would need to remove the existing resistors, and use the 3K and 6.2K resistors meant for Zone Doubling.
Just watched the Vista 20P zone doubling video. It seems the installer is putting the resistors in series. Because of this I assume they are not end of line resistors, just resistors of different values used for zone doubling. If a job has EOL resistors installed in parallel at the door/window contacts you would still need the series resistor to differentiate the zones correct?