Pico paired to one dimmer is controlling multiple dimmers

I'm sure this is a feature, but it isn't one I wanted. I installed a Caseta dimmer and 3 Pico remotes, after setting up my hub, to replace four Lutron Maestro switches (a dimmer and 3 wired remotes) controlling the main lighting in one room. When I installed the pico remotes, I paired them all with the dimmer before mounting them in their wall brackets. Some weeks later, I installed another Caseta dimmer in a single-pole controlling some accent lighting in the same room. I did not install any remotes, and I did not pair the existing Pico remotes, that had previously been paired to the first dimmer, to the new dimmer. I've been accustomed to just controlling the lights via the Amazon Alexa skill for Lutron. But today, I actually tried using one of the Pico remotes to control the main lighting in this particular room. To my surprise and dismay, the Pico ALSO activated the second dimmer, and turned on the accent lights.

Both the main lighting and the accent lighting are in the same "Room" in the Lutron app on my SmartPhone. But I never paired the remotes to the accent lighting dimmer. It just somehow decided that all the Pico remotes paired to the main lighting dimmer in that room would also control the accent lighting dimmer.

I do not want this behavior at all. How do I fix this? Do I have to re-pair the Picos to the correct dimmer? Is this something I can fix from the app? Why is this even happening? Did I do something wrong, when I installed the new dimmer that made the hub believe the remotes should be used to control both the first and the second dimmer? I can see that this would be a feature, if that was what someone wanted, but it should be an OPTIONAL feature, and the remotes should remain paired ONLY TO the dimmer(s) they were originally paired with.

I'm not sure why this is "default" behavior, but I found out how to fix it. I had to "Edit Device" for each affected remote, in the Lutron app, and REMOVE the association to the dimmer that was automatically added without my consent, by virtue of being in the same room as the other dimmer switch. I can see why this might be a desirable OPTIONAL feature to allow people to ENABLE, but making it a DEFAULT behavior -- without so much as issuing a simple warning that this is being done automatically -- seems like a very poor choice.