I am using something called jAlbum to produce image galleries. This requires an iFrame in HTML on the relevant page.
I create a custom HTML, add to my page, add the relevant code and great it works.
So I create the next page and create a new HTML custom component. Firstly I cannot rename it the so it is impossible to distinguish from the first one and secondly if i change the iFrame code in one, it changes the other as well - so I cannot have more than 1 HTML component in a site!