Pretty sure. I check in on our main-router each day, its always updated and I also have wireshark to look at traffic if I want to. We have 6 routers all in all, but the other 5 are all set in AP mode (cable connected - none is on wireless AP).
I cant see any suspicious traffic from the two chromcasts we have in the network either.
I reboot the mainrouter once every day (automatically) and manually from time to time when I see this issue. I don't have the multiple mac address on a single IP for anything else than the two chromecasts (one attached on the WLAN from the main router, the other one is on an AP)