To confirm, I do not have any controllers other than the CM15 installed. I don't have any RF controllers. I did notice yesterday that the transceiver in the CM15 was set to AUTO and have turned that off.
Here's how my house is configured:
Power comes in to a 200A main breaker box in the basement. This is where the circuit that runs to my office, and the CM15, is connected. The run to my office is roughly 75 feet. Several devices I control (orchid case lights, aquarium lights, Tempest video game) are in my office, on another circuit, so that's another 75 feet back to those devices.
For other, older parts of the house, it's even worse. There is a secondary 100A breaker box on the north end of the garage that used to be the house's main panel. It is now fed from the main box in the basement, and it's also about 75 feet from it. It is feeding circuits back in the main house, some of which are another 75 feet away.
So let's say my controller is sending a signal to the living room. It goes 75 feet back to the main breaker box, then 75 feet through the subpanel feed to the garage panel, then 75 feet back into the main house to the living room. That doesn't even count the possibility that the circuits might be on different legs of the 240V setup, which could really mess things up!
I was getting pretty poor reliability on transmissions to any of the devices in the living room when I first set up the system, so I added a Leviton X10 Signal Bridge at the garage box, and that sort of cleared up most of the problems in the living room, but I was still having occasional failures on the office devices, so I added a Leviton 2-phase Amplified Coupler/Repeater in the main breaker box to cover all my bases. This has worked very well since I installed it, and only started seeing some strangeness in the last week or so, when things won't turn off when they are told to.
Incidentally, I do have the "Repeat" option checked on all my timers, so I'm seeing three sends on all timer events.
I did look at my Activity Monitor this morning and am not seeing any of the really strange stuff showing up since rebooting the interface -- Just my timers going off (showing as ""Macro"). Fingers crossed.