jeth,
I know this thread is a bit old but...
I was looking over the date codes on your CM15a units.
However, I already have two AHP packages so I don't need another CM15A. One is date coded "86F26" and didn't come with very much else. The newer one is coded "04I38" although it was bought much more recently than that. It was part of a package deal that included all plugins "except" OnAlert.
The unit that you are calling new (date code "04I38") is actually very early CM15a. I have a unit with the same date code and it has a lot of problems dealing with RF due to the firmware revision.
Your other unit ("86F26") is probably a "06F26" manufactured in June of '06. Again, I have a similar dated unit. It responds much better to RF.
Be careful interchanging these units. Using an identical AHP file, these two CM15a's will respond differently.