Someone has told me they are getting 7+ identical texts when I send them a message. On my screen I only have 1. Any ideas? Phone company issue?

Very occasionally I get the same when I have received texts - About 5 copies of the same thing.

What network, phone & messaging app?

My Samsung did this when receiving texts until I updated it. New firmware did the trick.

Check with your phone company, as mentioned it might be your phone, but equally it might be a network problem, I received 20+ identical texts (one almost every hour), from my son while on holiday in France (2009), despite him only sending it once; it could have cost him a fortune if I hadnt contacted Orange Customer support and reported the issue.