I am re-developing a an old site from the ground up with SEO in mind every step of the way and I am running into a few issues for which, at this point, I am not truly capable of making the decision so I am doing the research by posting here. For example, for SEO purposes, I want to have two main "silos" for EditFast.com 1) "editing" and 2) "writing". With that in mind I want to create four subdomains: 1) editing.editfast.com 2) writing.editfast.com 3) editors.editfast.com 4) writers.editfast.com Which brings me to my first hurdle, with these four subdomains, I run into the problem/question of where to put the content. Some content will fit under both subdomains which creates a conundrum I have not figured out yet. For example the "Grammar Resource" on EditFast can be used by all three client groups: editors, writers and clients. 1) I could simply place it under the primary domain "editfast.com" but then the SEO value of having it under a specific and appropriate subdomain is lost. However, in this case, ALL subdomains are appropriate for this topic, but if I place the content under all of them then we run into the duplicate content issue. This may sound like an insignificant problem and you might simply say, put it on the primary domain, but this is just an example, there are other topics that truly belong on two or three of the domains. It is important to get it right from the start so your feedback is appreciated . . . good or bad.
My first suggestion is to remove the duplicate contents. By changing the URL is not going to change anything. You can use canonical links to protect it.