Duplicate Postings

Help!! I don't think I'm in the right place for this, but I don't know where else to put it. I don't know what I've done, but the last couple of times I've posted or replied to a letter on your Forum I find it has duplicated. The one I posted last night I was able to go into 'Edit' and delete the second copy but the one I'd replied to didn't give me that option from the 'Edit'. Any ideas on what I may have done wrong, and how to stop it please? Thanks Rozanna