Why was my blog deleted, by Blogger, as spam?Some blog owners innocently create multiple blogs, to back up their main blog.
Unfortunately, having multiple blogs with the same content may make the blogs look like a spam blog farm - and Blogger detects and deletes spam blog farms.
I've been advising blog owners, for years, that Blogger blogs need informative, interesting, and unique content, to survive as Blogger blogs.
Scraped blogs - whether you scrape your own, or another person's - are a bad idea.
The general focus on "unique" is intended to discourage scraping. Blogger Help: Spam, phishing, or malware on Blogger discusses spam blogs.
Spam blogs cause various problems, beyond simply wasting a few seconds of your time when you happen to come across one. They can clog up search engines, making it difficult to find real content on the subjects that interest you. They may scrape content from other sites on the web, using other people's writing to make it look as though they have useful information of their own. And if an automated system is creating spam posts at an extremely high rate, it can impact the speed and quality of the service for other, legitimate users.In the past, Blogger has been focusing on blog owners who steal the work of other blog owners, ie, "scraping" - or who copy by permission, ie, "syndication".
Blogger Content policy defines scraping more explicitly.
Examining Blogger Content Policy, we see the problem expressed more vividly.
Spam: Spam takes several forms in Blogger, all of which can result in deletion of your account or blog. Some examples include creating blogs designed to drive traffic to your site or to move it up in search listings, posting comments on other people's blogs just to promote your site or product, and scraping existing content from other sources for the primary purpose of generating revenue or other personal gains.Having backup blogs can look like "blogs designed to drive traffic to your site or to move it up in search listings". This is a technique, used by spammers. Why bother to write content? Just use some of the clones, as clones - both to backup each other, and to boost search engine results.
Duplication of content, online, hastens classification as spam.
Backing up a Blogger blog actually duplicates Bloggers efforts. Blogger / Google stores content - ie, your blog - in a cloud of servers, worldwide. If any one server goes out of service, the others are there, to provide immediate backup. You will, likely, never even notice if any one Blogger server goes down.
Alternately, a blog owner might backup a blog because of the spammer publicised unfair blog deletion policy. Here, the blog owner is playing into the spammers hands. If backup blogs were permitted, spammers could publish their spam blog farms with impunity.
Here, what the blog owner wants to plan for by having duplicates, unfair deletion, actually hastens the unfair deletion. This will happen, even if you make the "backup" blog private.
Classification of duplicate content, as abuse, isn't spurious.
If you think about it, a blog classified as spam, because of multiple clones, isn't actually spuriously deleted. If your blog gets a spurious classification, as a possible spam host, you have to appeal the classification. Creating a new blog, with identical content, just makes you look like a non repentant spammer - and increases your vulnerability.
If you want to retain comments and posts, export to an offline file. Just don't spread duplicate content across the Internet.