Txts are received on 2 separate iphones

My daughter just showed me some random txts she received from an unkown number. I recognised the content as coming from a colleague of mine, and checked my iphone. Sure enough, I had received the txts too.

The iphones have different sims & numbers, and my colleague does not have my daughters number. The only significant thing in common is that my daughters iphone is linked to my icloud account so that I can track her (Find iPhone), so perhaps somethings gone awry with the cloud or is it an issue with my provider - Vodafone??

Anyone else encountered this?