WordPress multiplied images 26 times

Hi!
Recently I moved an installation to another server. While I had over 6000 files, I just discovered that my new install has 28000 files aprox. I’ve discovered that there’s 26 versions of every uploaded image which weren’t there after moving the website.

I don’t know what could have caused this and I don’t know which is the better way to solve it.

Could anybody recommend me a plugin to erase all the extra files?

Help will be too much appreciated!