Why is my work iPhone receiving texts from my personal iPhone?

I have had a couple of weird experiences this week. First, I received a FaceTime request/call simultaneously on both my work and personal phones. I thought it bizarre, even more so since the request came from the account of a family member (hername@icloud.com) that doesn't use anything with FaceTime on it and doesn't have an icloud account. I confirmed later that she hadn't tried to call, which just made the whole thing weirder. Today, I received a text from my kid's school on both phones with about a 3 second delay between them. It doesn't happen both ways, only my personal alerts show up on my work phone, I haven't had one from work show up on my personal phone.

My personal iPhone is an iPhone 11, my work is an iPhone X and both are running iOS 13.3. They do not share an Apple ID and I've never used one phone's ID on the other. School doesn't have my work number - it's for work only. Family doesn't have my work number, aside from my wife. I have sent a few emails and an occasional text between the two phones. They have never been synced to the same computer. The phone numbers are not even remotely similar. The only things the phone have in common are the carrier (sort of, one is AT&T and the other is FirstNet, a division of AT&T) and me, the person that actually carries them. Neither phone has access to the other's email account. I Googled this and the answers I found don't apply.