A common enough request in the WordPress forums is people wanting to have two sites on a MultiSite network have the same content. Usually I take the time to ask why they’re doing this, and see if there are better ways around it. Like if you want to have a collection of ‘all’ posts, then you want WordPress MU Sitewide Tags Pages (weirdest name ever) or Diamond MultiSite Widgets, both of which help you do that admirably. And if you want to have the same ‘about’ page on multiple sites so they can keep their per-site branding, I point out that best companies don’t do that, they link home to mama. Amazon.com’s subsites all link back to amazon.com’s about page, after all. That’s good business practice!
Now, before someone gets all het up with an angry comment, there are good reasons to duplicate content, but it’s never 100% in the same language. If you have a site that needs to be bilingual, chances are you’re going to have a copy in English and (let’s say) French that, if translated would be pretty much the same. Not 100%, because of what idioms are, but basically the same. That’s a great reason for a duplicated site. Regional stores, where most of the content is the same, but some are different, is another good one. And those really aren’t ‘duplicated’ content.
But imagine the guy who wants to have 50 sites with different domains (no problem), and they’re all the ‘same.’ Well. What? You mean I can go to example.com and example2.com and example3.com and they’re 100% the same? Same theme, same posts, same content? That seems silly, doesn’t it?
So why do they persist in doing this? Some people cite SEO reasons (“My site ranks better for this domain…”) and other say its regional (“I need a separate domain for Canada!”) and they’re pretty much all wrong. Unless your domains are offering up different content, you are going to lose SEO ranking and readers by having multiple, identical, domains.
In D&D (yes, I play it), we always say ‘Don’t split the party!’ For the gamers, this is good because everyone gets to play with everyone together. For the person running the game (GM or DM, depending on your flavor of game), they can talk to everyone at once. Splitting the party means half the time, some of your players have to leave the room and kill time while the other people get to do fun things. And then the game rummer has to repeat things for the next group when you switch places! It’s annoying and boring 50% of the time, and it causes duplication of effort.
Splitting up your visitors means you have to figure out how to push content that is identical. This is not difficult, but it can cause problems. Every time you edit a post, the PHP calls your database and overwrites things. Multiply that by however many places you’re overwriting, and that could slow down posting. But then you think about using something like Content Mirror, which pulls post data in from across sites. Sounds great, until you remember that the blog switching code isn’t efficient (i.e. slows things down), and that all the smart people tell you
switch_to_blog() is rough on caching.
All that aside, there are major reason you don’t want to duplicate content. The foremost is that Google hates it. So do you, by the way. Duplicating content is what spammers and splogs do. (The Illustrated Guide to Duplicate Content in the Search Engines.) For those who go “Hey, but I have the same content on my archive pages for dates and categories!” you should read Ozh on the ‘Wrong SEO Plugins.’. The tl;dr takeaway is that good themes already do this for you!
Second only to SEO is now you’ve given your users multiple places to have the same conversation. Cross-posting is never a good idea. You dilute your content by have multiple conversations about the same thing. Should I post on foobar.com or foobaz.com to talk about my foo? The more time your readers spend thinking about where to comment, the less time they’re engaging with your site. This is, by the way, one of my nagging dislikes about BuddyPress. With groups and forums and blogs, you can dilute your message. Thankfully, you can use the group page to pull in all those conversations to one place where people will see them, which helps a lot.
I put the question to my friends. Why would you want 100% content duplication on multiple sites, in the same language, just with different URLs? Here are there answers:
@ipstenu uh. misguided attempts at SEO in certain geographics?
— Paul Gibbs (@pgibbs) March 2, 2012
@ipstenu Plagiarizer working very diligently?
— Liv Moreno (@Adm_Hawthorne) March 2, 2012
@ipstenu only if the different domains are country specific. otherwise, NO GOOD REASON
— andrea_r (@andrea_r) March 2, 2012
@ipstenu the only reasons I can think of are for search purposes (re: the URL would pull in different results) and keeping an online backup.
— Brian Crawford (@briancrawford) March 2, 2012
— Jan Dembowski (@jan_dembowski) March 2, 2012
@ipstenu none whatsoever.. but people think they will get more traffic that way. I think Google will see that as duplication and penalize it
— Christine Rondeau (@bluelimemedia) March 2, 2012
@ipstenu Maybe they don’t realise they can redirect one domain to the other & think they have to duplicate to use 2 different domains?
— Taryn Wallis (@phenomenoodle) March 2, 2012